Whisk the eggs together with the sugar. Mix the flour, cocoa, and baking powder, then add to the whisked mixture. Pour the batter onto a 40×30 cm baking sheet and bake in a preheated oven at 180 °C for approximately 15 minutes.
Meanwhile, whip the whipping cream and mix the tvaroh with mascarpone and sugar. Gently fold in the whipped cream and refrigerate. Cut the cooled dough into 2 parts. Spread with the prepared cream and place the second part of the dough on top. Weigh it down and refrigerate to set.