Start by preheating your oven to 350 degrees Fahrenheit. This ensures that the cake bakes evenly right from the beginning. Next, prepare three 8-inch round cake pans by spraying them with cooking spray and dusting them lightly with flour. This step is crucial to prevent sticking.
In a medium bowl, sift together the flour, baking powder, baking soda, and salt. This process aerates the dry ingredients, helping to create a light cake. Set this mixture aside.
In a large mixing bowl, beat the softened butter until creamy, which should take about one to two minutes. The texture should become smooth and pale in color.
Add in the granulated sugar and continue to beat on medium-high speed for about three to five minutes, until the mixture is white and fluffy. This step incorporates air into the butter, contributing to a light cake.
Now, add the egg whites one at a time, mixing well after each addition. This ensures that each egg is fully incorporated before adding the next. The batter will gradually become smoother and richer.
Next, pour in the vanilla extract, milk, sour cream, and vinegar into the butter mixture. Mix on medium speed until everything is well combined. You should see a glossy batter forming.
Now, gently fold in the dry ingredients. Mix until just combined; be careful not to overmix as this can lead to a denser cake. You want to maintain that fluffy texture.
Divide the batter evenly between the three prepared cake pans. Bake them in the preheated oven for about 30 to 35 minutes. To check if they are done, insert a toothpick into the center of the cakes; it should come out clean.
Once baked, allow the cakes to cool in the pans for about ten minutes before transferring them to a wire rack to cool completely. This cooling period is essential for achieving the perfect texture.
While your cakes cool, prepare the frosting. In a large bowl, combine the mascarpone cheese and cream cheese. Using the paddle attachment on your stand mixer, beat until creamy and smooth. This will serve as the base for your frosting.
Slowly add the heavy cream while mixing on low speed. This helps to create a light and airy frosting. Once fully combined, add in the powdered sugar and vanilla. Beat on medium speed until smooth, adjusting the consistency as needed.
On a cake stand or plate, begin assembling your Chantilly Berry Cake. Place one cooled cake layer on the stand, spread a generous layer of the creamy filling on top, and add a layer of fresh berries. Repeat with the second layer, and once the final layer is added, frost the sides and top of the cake evenly.
If desired, pipe some of the remaining frosting around the edges for a decorative touch. Finally, garnish with additional berries on top for that extra pop of color. Chill the decorated cake in the fridge until you’re ready to serve. This allows the flavors to meld beautifully.
