Warm-Method 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 more before baking, set an oven rack in the lower third of the oven and preheat to 170°C / 340°F.
   
• 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.
   
• Baker's 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. You can also use 175 grams of all-purpose flour or pastry flour instead of the combination of 87.5 grams all-purpose flour and 87.5 grams potato starch. However, adding potato starch to the flour makes the cake more tender, which is why I prefer it.
   
• Combine 87.5 grams of all-purpose flour with 87.5 grams of potato starch and 3/4 teaspoon of baking powder for a tender sponge cake. Alternatively, for a straightforward mix, you can use 175 grams of all-purpose flour or pastry flour. Whichever blend you choose, make sure to sift the flour mixture a few times to get it as aerated and light as possible. This is the secret to achieving the delicate layers your cake deserves.
   
• Baker's Note: To make this sponge cake, I use a method where whole eggs and sugar are combined and then gently warmed over simmering water. This initial step is crucial as it dissolves the sugar completely. Once the sugar is dissolved and the mixture is warm at 40°C (104°F), it is then removed from the heat and whipped to the desired volume. This technique, warming before whipping, creates a more stable sponge mixture compared to traditional methods that use cold ingredients.
   
• Start by selecting a bowl that will be used for warming your mixture—like my go-to, the KitchenAid 3-Quart Stainless Steel Bowl. You'll need to ensure this bowl can sit comfortably over a saucepan without touching the simmering water beneath. If your stand mixer bowl doesn't fit well or ends up too close to the water, opt for a different mixing bowl right from the get-go for this step. Pour about 2 inches of water into your saucepan and heat until it's just simmering. 
• Put 225 grams superfine sugar, 7 large eggs (approximately 350 grams), and 1 teaspoon of vanilla bean paste into the bowl of a stand mixer. Set the bowl on top of the pot with the simmering water and gently stir it—not whip it. You’re aiming to heat it up to dissolve the sugar, not whip air into it. It’s best to use a digital thermometer to check the temperature. At 40°C (104°F), it should take somewhere between 1 to 3 minutes. If you don’t have a thermometer on hand, you can test it by dipping a finger into the mixture to make sure the sugar’s fully dissolved—it should feel slightly warm to the touch.
   
• Remove the bowl from the pan and place it onto the stand mixer. Using the whisk attachment, whip on medium-high speed for 8 minutes until the mix is thick. When the volume has increased by at least 3 times, lift the whisk and let the mixture flow down like ribbons. If the ribbons appear for 3 to 4 seconds, it's reached the ribbon stage.Turn the speed down to low speed for 3 minutes more to stabilize the foam. Remove the bowl from the mixer.
   
• When adding the flour mixture fold confidently and with strength! You want to be gentle to keep it fluffy but thorough so it’s nearly all mixed in or you end up with a dense sponge cake. Start by sifting half of the flour/potato starch mixture over the foam, then carefully fold it in with a balloon whisk. Do the same with the rest of the flour mixture, folding until it’s totally incorporated. Scrape the bottom of the mixing bowl with a silicone spatula to make sure all of the flour is integrated.
   
• Divide the cake batter between the three round baking pans. Use a scale! Smooth the surface with an offset spatula.
   
• Give your pans just a really good spin on the table; what that does is it takes the cake 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. So, don't be afraid to really give it a good spin. Get that batter moving up. 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 springs back when pressed lightly in the center, about 12 to 15 minutes, depending on your oven and baking pan. Mine was done at 13 minutes. To check if the sponge cake is ready after 12 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. At the 13-minute mark, if the center seems almost set, 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.
   
• Remove the cakes from the oven and immediately without any delay, run a knife between the sides of the pan and the cake, and invert the cakes immediately onto a wire rack; remove the parchment paper and leave them to cool completely on the wire rack.
   
• Repeat with the final layer.
   
• Cover the cooled cake layers with plastic wrap or in a large ziplock bag to prevent them from drying out until you are ready to use them.
   
• You can bake the sponge cake layers up to a month in advance and freeze them. After the cake is completely cooled to room temperature, wrap each individual cake layer with 2 layers of plastic wrap, followed by tin foil, or place it in a ziplock bag. Before using your cake layers, remove them from the freezer about an hour before you plan to fill the cake.
   
• This vanilla sponge cake is a great match with cream-based fillings, mousse, ganache, pastry cream, curd, and fruit jam. (Buttercream is not a great match).
   
• As always, the texture of sponge cake improves after you fill the cake with a cream-based filling; it rests in the fridge for a few hours or overnight, and the flavors have a chance to mingle and make the sponge cake extra soft.