This strawberry mousse recipe gives you three different ways to make it, each with its own special strawberry flavor. You can choose from:

Roasted Strawberry Purée: Roasting strawberries is a great way to bring out a stronger, more delicious strawberry flavor.

Reduced Strawberry Purée: Blend strawberries and then cook the mixture on the stove to make the strawberry flavor even richer and more pronounced. For this cake I used reduced strawberry to make the strawberry mousse for this cake

To ensure both recipes progress smoothly and their downtimes overlap efficiently, begin with either the Roasted Strawberries Puree or the Reduced Strawberry Puree. Once you've started on that, move on to preparing the strawberry mousse. After preparing the mousse, put it in the fridge to chill. While the mousse is setting, you can then start working on the cake layers. This sequence will help you manage your time and tasks more effectively.

 Fluffy Vanilla Sponge Cake

• When preheating the oven for my cakes, always use the 'top and bottom heat' setting. Please avoid using the fan-forced option, unless otherwise specified.
   
• Twenty minutes or longer before baking, set an oven rack in the center of the oven, and preheat the oven to 170C°/ 338F°. Using an oven thermometer will ensure even baking results each time, as every oven is different. Always go with the reading on your oven thermometer rather than the temperature you set on your oven.
   
• Grease your wire racks lightly with butter and set them aside; this step will prevent the cake from sticking to the wire rack.
   
• Use a small piece of cold butter, and gently rub the cold butter over the bottom and the sides of three 20 cm ( 8-inches) round baking pans. This technique of using a small piece of cold butter ensures an even, ultra-thin coating. Place a circle of parchment in the bottom of the pan. Add a tablespoon of all-purpose flour and tap it around the inside of the pan until all the buttered surface is covered 100%, then turn the pan upside down over a sink and tap out the excess flour. If you don’t have three pans, it’s okay to bake the cakes in stages; The cake batter will be kept at room temperature until needed.
   
• Bakers note: The egg white to yolk ratio in an egg can vary to such a degree. Therefore, weighing the egg yolks and egg whites as mentioned in the recipe and adding or reducing them if needed is advisable. Place 7 large eggs in lukewarm water for a few minutes.
   
• Bakers Note: All-purpose flour with 8-9% gluten is ideal for tender sponge cake layers; I use 9%. While 10% works, less gluten is preferable. Enhance tenderness by mixing in potato starch which is labeled as potato flour in Scandinavia.
   
• In a medium bowl, sift together 90 grams of all-purpose flour or pastry flour, 90 grams of potato starch, and one teaspoon of baking powder. To get the cake you truly deserve, sift the flour mixture twice to make the flour as aerated and light as possible.
   
• For the yolk mixture, in the bowl of a stand mixer fitted with the whisk attachment, whip 50 grams of superfine sugar, 140 grams of egg yolks, and two teaspoons of vanilla bean paste on medium speed until pale yellow, tripling its volume, and all of the sugar is dissolved—about 5 to 8 minutes. Set aside for now.
   
• Wipe a stainless steel bowl and the whisk of an electric mixer with a paper towel dampened with a little lemon juice to eliminate any trace of grease.
   
• Put 210 gram egg whites and a pinch of cream of tartar into the bowl. Using the whisk attachment, whip on medium high speed for about 3 minutes until the whites are glossy white. Add the sugar ( 200 grams) one tablespoon at a time over 3 minutes to make a very shiny and stiff meringue. Remove the bowl from the mixer.
   
• As soon as the meringue is done, place the whipped meringue into a large bowl, add the whipped egg yolk mixture on top, and carefully fold them together using a balloon whisk rather than a spatula. You don't want to deflate the mixture, so try to do as little folding as possible.
   
• Sift the flour/starch mixture onto the egg mixture in two increments. For maximum volume, use a balloon whisk or a large silicone spatula, and gently yet confidently fold the flour into the batter with strength! It’s better to make a few powerful folds than 15 half-hearted ones. If you don’t get it mixed in just right, you might end up with a sponge cake that’s all heavy at the bottom and too fluffy at the top. You’ll know you’ve done it right when the batter gets a bit less puffy and looks more uniform.
   
•  Use a large silicone spatula at the end of the folding to reach the bottom of the bowl and scrape the batter into the pan(s).
   
• Evenly distribute the batter among the three prepared pans, about 250 grams in each baking pan. Use your offset spatula to spread it into an even layer.
   
• Bakers Note: Give your pans just a really good spin on the table, what that does is it takes the batter up the side of the pan a little bit, just so that as it's baking, it already has an attachment to kind of move up the side of the pan. Don’t tap your baking pans on the kitchen counter to try to get things to level out, especially with this style of cake batter, because banging your pans or dropping it on the table to level the batter actually gets rid of all the air bubbles that you just incorporated into the batter. 
   
• Bake both cakes until golden brown and the top of the cake feels firm and has a pale golden colour. about 15 to 17 minutes, depending on your oven and baking pan. Mine was done at 16 minutes. To check if the sponge cake is ready after 15 minutes of baking, you should first look through the oven window rather than open the oven door. If the center appears slightly sunken, give it a minute or two longer while keeping an eye on it. Then carefully open the oven and gently press the top of the cake. It should feel firm to the touch and may have a slight bounce to it. This method allows you to monitor the cake's progress without disrupting the baking process. Because this sponge cake is going to be filled  with a cream based filling, it doesn't matter if you overbake it for a minute longer, It's better to do that than end up with a sponge cake that is wet in the bottom.
   
• Immediately without delay run a knife or metal spatula between the sides of the pan and the cake, and invert the cakes onto a prepared wire rack, remove the parchment paper, and leave them to cool completely on a wire rack.
   
• Repeat with the final layer.
   
• If not used immediately, wrap them well in plastic to keep them from drying out.
   
• Each cake layer is about 4 cm high.
   

Roasted Strawberries (Option 1)
 

• Heat your oven to 190°C (375°F).
   
• Choose bright red strawberries, ideally picked in summer, for their sweetness and bright color. This ensures your strawberry mousse has a deep strawberry flavor and looks pretty in pink. The ripest strawberries give the best taste.
   
• Prepare 350 grams of strawberries by removing the stems and cutting them in half. Arrange them in a baking dish that´s deep enough to catch all the juices. Sprinkle with 1 tablespoon of sugar and a pinch of salt to bring out the flavors.
   
• Bake for 30 minutes at the center of your oven, stirring every 10 minutes to cook evenly and prevent the juices from caramelizing or burning.
   
• Cool slightly afterward. Blend the strawberries iin your blender, strain to remove seeds, and chill for a cold, smooth strawberry mousse base.

 Reduced Strawberries ( option 2)
 

• Baker's Note: When strawberry season arrives and those vibrant, ruby-red strawberries are available, make the most of their natural sweetness and flavor. If you're lucky enough to have in-season, ruby-red strawberries, their flavor is so intense that reducing the strawberry purée isn't necessary, 125 grams of pure seedless strawberry purée is enough for this strawberry mousse. This method works especially well with ruby red strawberries, known for their vibrant color and exceptional flavor. During strawberry season, I often prepare large batches of purée from peak-season strawberries and freeze it in small containers. This way, I always have high-quality strawberry purée on hand all year around. The intense flavor of these strawberries is so perfect, there's no need to reduce the purée at all.
   
• To reduce strawberries: Take 400 grams of fresh strawberries, the redder and more in-season, the better. After blending them smooth and straining out the seeds, put the purée in a saucepan on medium-low heat, stirring occasionally until it reaches the consistency of ketchup. The main thing here is to focus on the taste. Start with a taste test before you heat it, and keep trying it as it simmers. You’re looking for that point where the flavor just pops and tastes way better than at the start. Strawberries aren’t all the same; some have more water, some less. So, while you’re aiming to cook off some of that water to concentrate the flavor, don’t get too hung up on getting it exactly as thick as ketchup. It might be a bit thinner, and that’s okay. The goal is a purée that tastes amazing – more strawberry, less water. My batch was done in just over 20 minutes.
   
• Allow the reduced strawberry puree to cool, then chill it in the refrigerator until needed.
   
•  Your strawberry reduction can be stored in the refrigerator for up to 1 week. Ensure it's in a tightly sealed container to maintain freshness and prevent it from absorbing other flavors from the fridge.

Strawberry Mousse
 

• Bakers Note: Use only heavy cream (or heavy whipping cream) with a 40% fat content. This higher fat content is key for whipping up a cream that's both thick and stable, providing the perfect base for your frosting. Ensure the cream is very cold for optimal whipping; placing the cream in the freezer for about 15 minutes before use can enhance the whipping process.
   
• Opt for a full-fat, natural Greek-style yogurt with a 10% fat content. The thick consistency of Greek yogurt, achieved by straining out the whey, makes it an ideal choice for creating a rich and creamy strawberry mousse. Avoid low-fat or fat-free yogurts, as their higher water content can result in a frosting that's too runny for your liking. Your Greek Yogurt should be notably thick. If you find the yogurt too watery, a simple fix involves straining it through a fine-mesh sieve over a bowl, covered with plastic wrap, and left to drain in the fridge for a few hours or, ideally, overnight. This step is crucial to ensure your strawberry mousse achieves the perfect consistency, avoiding a watery outcome that could compromise your frosting's structure.
   
• In the bowl of your stand mixer fitted with the whisk attachment, combine 100 grams of powdered sugar, 350 grams of cold Greek yogurt (10% fat), the finely grated zest of 1 lemon, 350 grams of cold heavy whipping cream (40% fat), and one or two teaspoons of vanilla bean paste, or the seeds scraped from one vanilla bean. Whip this mixture on low speed for one minute, then increase to medium-high speed. Continue whipping until it becomes thick, fluffy, and holds its shape, which should take about 1 to 3 minutes. Be cautious to avoid overmixing, as the whipped yogurt frosting will soften and lose stability if beaten for too long.
   
• After the mixture has reached its desired thickness, add 125 grams of very cold strawberry purée, or 125 grams of reduced strawberry directly to the mixer. Whip the mixture again on medium speed just until the strawberry component is fully combined, about 10 to 20 seconds. This process ensures the strawberry flavor is evenly distributed throughout the mousse while maintaining its light and airy texture.
   
• The strawberry mousse should be slightly thicker than whipped cream and firm enough ( as long as you have used a cream with 40% fat and everything was super cold) to fill your cakes and will firm up more when inside your cake.
   
• Baker's Note: Adding Greek yogurt to the mixture of whipped cream and strawberry not only enriches the flavor but also contributes significantly to the mousse's texture. The Greek yogurt's thicker consistency plays a crucial role in how the strawberry mousse sets, especially when chilled. This combination ensures that while the strawberry mousse may initially resemble the lightness of whipped cream, it gains firmness and body as it cools in the fridge. So, if your mousse seems a bit loose right after mixing, rest assured. The addition of Greek yogurt will help it firm up beautifully, creating the perfect texture for your cake filling. Remember, patience is key—it will set perfectly inside the fridge.
   

To assemble
 

• Begin by placing the first completely cooled sponge cake layer on a serving plate that can fit in your refrigerator.
   
• Place a few large scoops of the strawberry mousse on top and carefully smooth it out with an offset spatula. Aim to keep the mousse within the center of the cake, not too close to the edge to prevent it from spilling over the sides.
   
• Arrange the thickly sliced or quartered strawberries on top of the mousse layer and add another scoop of strawberry mousse on top and and carefully smooth it out with an offset spatula. Place the second sponge cake layer on top, gently pressing to help it adhere to the strawberry mousse.
   
• Bakers Note: If you've gone closer to the edge with the strawberry mousse and it begins to spread out slightly, as shown in my photos, it's not a problem. Wrap a clear acetate cake collar around the cake at the end. This will help any strawberry mousse that has spilled over to set neatly against the cake by the time it chills.
   
• Repeat the process with the remaining strawberry mousse, strawberries, and a scoop of strawberry mousse and add the final cake layer.
   
• Wrap the completed cake with the acetate collar, and then with plastic wrap before placing it in the refrigerator.
   
• Chill the cake for at least 8 hours, or overnight, to allow the mousse to firm up and the flavors to meld.
   
• After the cake has set, remove it from the refrigerator, take off the acetate collar, and the plastic wrap. 
   
• Your cake should have neat layers with the mousse perfectly set within the edges. if any strawberry mousse has seeped out, just use your offset spatula to smooth it back against the cake for neat edges.
   
• Now, it’s ready to be decorated with your angel feather icing.
   
• Make the angel feather icing as outlined below, then add dollops on top of the cake, spreading it with an offset spatula and working it gently around the sides. While this cake keeps well for two days, it is at its best when served on the day it’s decorated.

Angel Feather Icing
 

• Wipe the inside of your bowl and the whisk attachment with a paper towel dampened with a bit of lemon juice to eliminate any trace of grease. Ensure the bowl and beaters are thoroughly clean; even the slightest hint of oil can inhibit the foaming.
   
• For best results, use fresh egg whites. Often, boxed whites don’t whip up as well. Ensure you cleanly separate the egg whites from the yolks.
   
• Fill a saucepan with 3 cm (1 1/2 inches) of water and place it over medium-low heat.
   
• In the bowl of a stand mixer, combine 100 grams of egg whites, 255 grams of white sugar or superfine sugar, 50 grams of water, 60 grams of glucose (or light corn syrup), a pinch of cream of tartar, and seeds from 1/2 vanilla bean (if using). Use a clean whisk to make a slurry.
   
• Place the bowl over the steamy water, stirring and constantly scraping with a whisk or spatula until all of the sugar is 100% dissolved. With gently simmering water, the meringue should cook fairly quickly; this step typically takes about 3 minutes. If you find the temperature climbing too slowly, you can increase the heat slightly.
   
• To check if the sugar is dissolved, rub some of the egg white/sugar mixture between your (grease-free) thumb and forefinger. If it doesn't feel grainy, your sugar is dissolved.
   
• Transfer the bowl to a stand mixer fitted with the whisk attachment. Whip on medium-high speed until the mixture is glossy, thick, and has tripled in volume, or until you are satisfied with the consistency of the Angel Feather Icing. This usually takes about 5 minutes.
   

With a hand mixer
 

• Baker's Note: Egg whites begin to coagulate at approximately 65°C/149°F, so make sure that the water is just at a simmer when you place the deep bowl into the saucepan. Start beating immediately at the lowest speed with an electric hand mixer as soon as you place the bowl into the simmering water, or you risk making scrambled egg whites!
   
• Put the 100-gram egg whites, 255 grams of sugar, 50 grams of water, 60 grams of glucose (or light corn syrup), a pinch of cream of tartar, and seeds from 1/2 vanilla bean into a spotlessly clean bowl. Use a clean spatula or small whisk to make a slurry.
   
• Baker's Note: Heating the egg whites over a pot of simmering water relaxes their proteins, enabling them to whip up higher and more quickly. The sugar also dissolves, resulting in a silky-smooth consistency.
   
• As soon as your water is at a simmer, turn off the heat and immediately place your bowl in the simmering water, ensuring it goes up 2 1/2 cm (1 inch) up the side of the bowl. Start beating immediately at the lowest speed with an electric beater until the sugar is 100% dissolved. (This takes about 3 minutes).
   
• "As soon as the sugar is 100% dissolved, continue to whip on medium-high speed (with the bowl still in simmering water) until the mixture climbs to the top of the bowl and the meringue holds a soft, floppy peak, about 4 minutes."
   
• Remove the bowl from the heat and continue beating at medium-high speed until the frosting is cool and you are satisfied with the consistency of the Angel Feather Icing. This takes about 3 to 5 minutes.
   
• For maximum freshness and deliciousness, use it immediately to decorate your cupcakes or cakes.
   
• The Angel Feather Icing keeps well on cupcakes or cakes at room temperature for at least two days.
   
• Remove the cake from the fridge, remove the cake ring and acetate sheet ( if using), and discard the plastic wrap.
   
• Place the cake carefully on your cakestand, and add dollops of the luscious angel feather icing on top.
   
• With a large offset spatula, frost the entire cake with angel feather icing, and use the back of a spoon to create a rustic finish.
   
• The Angel Feather Icing keeps well on your cake for at least 2 days.