Using butter, grease the bottom and sides of two 6-inch round cake pans or spring form pans. Line the bottoms with a round piece of parchment paper. To ensure even baking, place a bake even strip around the pan.
In a mixing bowl, combine the butter and sugar, beat using an electric mixer until fluffy. Add in the egg whites, beat again.
Add in the sour cream and vanilla paste, mix until smooth with a spatula.
In a smaller bowl, combine the flour, baking powder and salt, gently mix with a spoon. Gradually add half of the flour mixture to the wet ingredients, do not dump it in, rather take spoonfuls of the flour mixture and gently shake it over the wet ingredients as if you were sifting in the flour. Fold in the mixture until no flour remains. Repeat with the other half of the flour, folding it in and scraping the sides and bottom of the bowl to incorporate everything.
Divide the batter evenly between both pans, with about 1 & 1/4 cups of batter in each pan.
Bake for 22-26 minutes, or until a toothpick inserted in the center comes out clean.
Once the cake is done, allow it to cool in the pan on a cooling rack for 10 minutes. After 10 minutes, carefully remove the cake from the pan. If using a springform pan, remove the sides and bottom. Allow the cake to cool completely on a cooling rack. Once cool, remove the parchment paper round from the bottom of the cake. If you need to level the top of your cake, do so now using either a cake lever or knife.
Make sure the cake is completely cool before moving forward.
If you'd like to make the cake several days in advance, wrap it in plastic wrap and store in the refrigerator.
Ice Cream
In a metal mixing bowl, use an electric mixer to beat the heavy cream to stiff peaks, about 2 minutes.
Add in the sweetened condensed milk and vanilla paste. Mix well with a spatula.
To assemble the ice cream cake
Place one layer of white cake in the bottom of a 6 inch springform pan. If you do not have a springform pan, use a regular 6 inch round pan lined with plastic wrap that hangs over the sides. This will help you remove the cake from the pan once frozen.
On top of the first layer of cake, add the homemade ice cream. Swirl in the blueberry and strawberry sauce/jam, adding as much or as little as you like. If using fresh fruit, mix the fruit into the ice cream and then add on top of the first layer of cake.
Place the cake in the freezer for 30-60 minutes to harden the ice cream before adding the second layer of cake.
Place the second layer of white cake on top of the ice cream layer. The cake will stick up past the sides of the cake pan.
Allow the ice cream cake to freeze completely, 6-8 hours.
Once frozen, carefully remove the sides from the springform pan. You may find it helpful to use a flat metal spatula to go around the edges of the pan to loosen the cake before removing the springform pan.
Use a small offset spatula to add a thin layer of cool whip to the sides and top of the cake. Don’t completely cover the cake layers as they are suppose to still be visible.
Return the cake to the freezer and keep frozen until ready to serve.
If desired before serving, decorate the cake with fresh blueberries, strawberries, blackberries, baby’s breath and small red roses.
