Melt butter and chill. Use a mixer to combine butter, sugar, cocoa, eggs and flour.
Turn on the oven 180 degrees, let it heat up. Grease the baking dish with butter and put the resulting dough into the mold. We level.
Now we are preparing the mascarpone cream. Mix well the cheese, sugar and egg until smooth.
Gently spread the cream over the dough layer. Mix the white and brown layers a little with a fork in a circular motion to get beautiful streaks. We set to bake for 40-45 minutes.