Berries-And-Cream Mini Layer Cakes

Make the cake: Preheat the oven to 350u0b0F. Grease a 13 x 18 inch baking sheet with nonstick spray, line with parchment paper, then grease the parchment paper.
In a medium bowl, whisk together the flour, baking powder, and salt.
In the bowl of a stand mixer fitted with the whip attachment, whip the eggs, egg white, and sugar on low speed to combine. Turn speed up to high and continue to whip until the mixture is slightly more pale and very thick, 5 minutes. Reduce the speed to low and whip for 1 minute more.
Sprinkle about 1/4 of the flour mixture over the egg mixture and mix on low speed just until incorporated. Add the remaining flour in 3 additions.
Gradually drizzle the cream into the batter, mixing just until incorporated. Add the vanilla and mix to combine.
Pour the batter into the prepared pan and spread into an even layer. Bake until the cake springs back lightly when touched in the very center, and a toothpick inserted into the center comes out clean, 17-20 minutes. Cool completely.
Use a 2 inch round cutter to cut 27 rounds from the cake. Set aside.
Make the filling: In the bowl of an electric mixer fitted with the whip attachment, whip the cream to soft peaks. Add the powdered sugar and vanilla and continue to whip to medium peaks.
To build the cakes, place about 1 tablespoon of frosting on each layer, and stack the cakes three layers tall. Scoop another tablespoon of frosting on top and garnish each with berries.