This strawberry mousse recipe gives you two 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. After roasting, make a purée with all the roasted strawberries

Reduced Strawberry Purée: Blend strawberries and then cook the mixture on the stove to make the strawberry flavor even richer and more pronounced.

Yellow Cake Layer
 

• 30 minutes or longer before baking, set an oven rack in the lower rack of the oven. Set the oven to 150C°/300F° or fan setting to 135C°/275F°
   
• Grease a 30 x 40 cm ( 12 x 16 inch) rimmed baking sheet and line it with parchment paper; press the parchment so it sticks well to the baking sheet so the parchment paper won't move around when you spread the cake batter.
   
• Before you start, make sure the butter is at room temp; if your butter is too cold, it won’t whip up light enough; but if it’s too soft, it can’t hold enough air to leave a cake. You will know it’s right if it is soft but still holds its shape when you pick it up. If the butter droops or your finger melts right into it, it’s too soft.  If you can easily press your fingers into the butter, it's too cold.
   
• For this recipe, You need 6 large eggs divided.
   
• For the yellow cake layer, In the bowl of a stand mixer fitted with the whisk or paddle attachment, beat 150 grams of unsalted butter, 175 grams of superfine sugar, and 2 teaspoons of vanilla bean paste fluffy on medium speed; this takes about 3 to 5 minutes. It's super-tempting to turn the mixer on high speed but resist the urge.
   
• Make sure to stop the mixer at times and scrape down the bowl a few times while mixing.
   
• Make sure your 6 large yolks are at room temp, or the perfectly whipped butter will seize, and you’ll lose the fluffy air you created, Add 120 grams of egg yolks one at a time, mixing until each is incorporated before adding the next. Mix until combined. Scrape down the bowl.
   
• In a medium bowl, sift together 150-gram all-purpose flour or pastry flour, or cake flour and 1 1/2 teaspoons baking powder.
   
• Sift in the flour mixture in three batches and carefully fold in using a silicone spatula; lastly, add the 100 grams of whole milk or heavy cream, or sour cream and fold again until fully combined.
   
•  The cake batter will be somewhat thick. 
   
• Gently spread the yellow cake batter using a spatula evenly and thinly across the baking sheet, it may seem like there is not enough cake batter to make a full cake but take your time, and it will spread out with a little patience, and the cake will rise some while baking.
   
• Set aside while you prepare the meringue mixture.

Meringue Layer
 

• Wipe the inside of a mixer bowl, as well as the whisk attachment, and hand whisk with a paper towel dampened with a little lemon juice to eliminate any trace of grease.
   
• Bakers note; Mixing at medium speed creates a more stable meringue. High speed will cause them to foam more quickly, but they will be less stable and hold the air as well. And it is important that the sugar is added in very slowly and only after the egg whites are already starting to hold soft peaks. This helps keep the meringue stable.
   
• In a clean bowl of a stand mixer fitted with the whisk attachment, put 180 grams of egg whites and a pinch of cream of tartar; whip the meringue on medium speed until the meringue is white, glossy, and holds a soft peak before adding any sugar. This allows the meringue to keep its volume and not deflate when adding the sugar.
   
• Then, add one tablespoon at a time of the 300 grams of superfine sugar. This step takes approximately 3 minutes. Never add all the sugar at once when creating a meringue.
   
• After all of the sugar is added, continue whipping for 10 full minutes on medium-high speed until the mixture has tripled in volume, is thick and glossy, and the sugar has dissolved. Use a timer! Do not overmix, or the meringue can collapse when it comes out of the oven.
   
• Remove the bowl from the mixer and add 1 teaspoon vanilla bean paste if using and use a spatula to combine. 
   
• Spread the meringue evenly on top of the yellow cake batter with a silicone spatula.
   
•  Sprinkle the coarse almonds evenly across the meringue.
   
• Place the baking sheet in the lower rack of the oven and bake for 35 to 45 minutes until the meringue is dry and lightly golden or until a skewer inserted in the middle comes out clean, and the meringue is firm.  Mine was done at 45 minutes.
   
• Leave to cool for one minute in the pan, then turn out carefully so the meringue is still on top.
   
• Leave to cool completely while you make the strawberry mousse.
   
• The cake is less fragile if cooled completely.

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 in your blender, strain to remove seeds, and chill for a cold, smooth strawberry mousse base.

Simply 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, 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
 

• To assemble, cut the cake into two halves crosswise with a serrated knife. 
   
• Take one half and peel it from the parchment paper; gently turn it.
   
• Place the first layer of cake with the meringue side facing down ( It´s important that the meringue layer is facing down) on a serving tray or on a baking sheet covered with parchment paper; make sure the serving tray or baking sheets fit into your fridge.
   
• Spread 3/4 or all of the Strawberry Mousse evenly on top of the cake layer; add 150-gram slices of strawberries, and add the remaining strawberry Mousse on top. Then carefully layer the other half on top. Press lightly.
   
• Serve immediately for an amazingly soft and delious cake with a cream-like strawberry mousse. To soak up the strawberry mousse and make it firmer and make the yellow cake layers softer and so moist. Place the cake in the fridge for a few hours before serving.
   
• The meringue layer will stay mellow, and the cake layer will stay soft. After the cake has been in the fridge, the strawberry mousse gets more firm and gives you a melt-in-your-mouth texture.
   
• Just before serving, remove the cake from the fridge for about 15 minutes before serving. Cut slices with a serrated knife.
   
• The cake is at its best when eaten within 24 hours but still delious on days 2 and three.