How to make
Beat the eggs with sugar until whitening and successively add the butter, milk, sifted flour with vanilla and baking powder. Beat everything until homogeneous and then add the orange peels and essence. Grease and flour a cake form.
Divide the mixture in 2 and put a few tablespoons of cocoa in one. First put the cocoa mixture in the form, and after it - the yellow one. Bake in a preheated moderate oven, check if it's ready with a stick. Do not open the oven frequently.
Let the finished cake cool, remove it from the form, cut it and serve sprinkled with powdered sugar.
