How to cook
Beat the egg yolks with half the sugar until you get a smooth and fluffy cream. Add the vanilla and gradually the sifted flour, starch, cocoa and baking powder, all while stirring constantly. Separately, beat the egg whites into hard snow and gently mix them in with the rest of the mixture in parts, until everything becomes homogenized.
Prepare a large, oval tray. Lay it out with baking paper and pour on half of the mixture for the layers. Bake the first layer until a toothpick comes out dry in a preheated 356°F (180 °C) oven, being careful not to burn it because it does bake fairly quickly. Do the same for the second layer.
Let both baked layers cool completely. Cut the cooled layers very carefully in 2 using a string or a very sharp knife. The result is 4 large layers.
Crush the chocolate in a bowl for the chocolate mousse. Soak the gelatin in cold water to swell. Separately, beat the cream into snow, then put the milk to heat up. To the hot milk, which you have removed from the stove, add and stir with the gelatin. Then mix the gelatin milk into the chocolate and stir until everything is homogenized. Let the mixture cool completely and gently mix it with the whipped cream.
For the white cream, soak the gelatin in the water to swell. Melt it in a water bath without boiling. Beat the dairy cream into snow and mix the sour cream well with the sugar. Combine both creams and add the cooled, melted gelatin to them. Allow both creams to cool until slightly firm and not runny, but not completely solid.
In a suitable baking tin with walls, put the first layer, smear it with the white cream and scatter drained cocktail cherries on it. Then place the second layer, all of the chocolate mousse, the third layer, white cream with cherries once again and then the fourth layer. Lightly press down on the cake so that the cream sets in place. Here the walls of the baking tin are key, which will retain the shape of the cake. If you do not have a baking tin with walls, you can make the walls from a piece of sheet iron.
Put thus prepared cake in the refrigerator for several hours until completely tight. Then take it out and remove the walls of the tin. For the glaze, heat the cream and butter in a container in a water bath on the stove and mix it with the crumbled chocolate. Leave it aside to cool, next pour it over the cake evenly.
Once the glaze tightens, you can make a decoration for your black and white wedding cake according to your taste by spraying on confectionery whipped cream and arrange ready-made fondant roses, which can be found in pastry shops.