Make a batter from butter, sugar, eggs, 1 cup of sour cream, flour and baking powder. Spread half of this dough on a prepared baking sheet. Stir 2 tablespoons of cocoa powder into the other half and spread this dough onto the light colored dough. Top with the drained cherries.
Bake the sheet cake on the middle rack in the preheated oven at 170 ° C for about 25 minutes (make a stick test). Then let cool slightly.
Mix the remaining 3 cups of sour cream with 4 tablespoons of sugar and spread on the cake. Finally sprinkle with cocoa powder. Let it steep until serving.