Set oven to 350°F and preheat for 15 minutes. Line the bottom of three 9-inch nonstick springform pans with parchment paper. Grease or spray the sides of the pans, and wipe the edges with a paper towel. Set them aside for later use.
Use a mixing bowl and electric mixer. Beat egg yolks, whole eggs and sugar for 5-7 minutes until light and fluffy.
Add sifted flour to the batter and gently fold in with a spatula for 1-2 minutes until just combined.
Divide Batter into evenly two portions.Pour each portion into greased cake pans. Bake for 20 minutes .
After baking the cake, gently run a thin spatula around the edges of the springform pan to loosen the cake layer. Then, remove the rim of the pan. Place the sponge on a cooling rack and let it cool completely before frosting.
Cut 6 large fresh strawberries and 3 fresh kiwi into thin slices.Use a mixing bowl and whisk. Mix sour cream, Cool Whip, sugar and vanilla extract for 3-5 minutes until smooth.
Cut out a cardboard circle the same size as the cake and wrap it in foil. Spread a teaspoon of frosting on the foil to secure the first cake layer. Add about 4 tablespoons of frosting on top of the first layer and top with sliced strawberries. Repeat the process for the second layer, using kiwi slices instead of strawberries, or mix both fruits on each layer if desired.
Use a pastry scraper to smooth out the edges and the top of the cake for a finished look.Slice strawberries and kiwi with a knife. Arrange fruit decoratively on the frosted cake top.
Refrigerate the assembled cake for at least 1 hour before serving to blend the flavors.
