Day and Night Cake

For the classic sponge, separate the egg whites from the yolks. Whip the whites with sugar until stiff peaks form, then beat in the yolks one at a time. Fold in the baking powder, vanilla, and sifted flour using a spatula. Pour into a cake pan and bake at 350°F (180°C) for 30–40 minutes (check for doneness with a toothpick).

Prepare the chocolate sponge the same way, but mix the cocoa powder into the flour before sifting. Bake under the same conditions.

For the frosting, whip the softened butter until fluffy. Add the condensed milk and beat thoroughly again until smooth.

For the milk soak, mix the warm milk with condensed milk.

Let the baked sponges cool completely, chill for 8–10 hours, and then cut them into individual layers. Assemble the cake by alternating the layers—light, then chocolate—soaking each layer and spreading frosting between them.