Sift flour with baking powder.
Butter and broken chocolate is melted in a water bath to a homogeneous consistency. Stir, cool slightly.
In a mixer at high speed, beat three eggs and 150 grams of sugar until fluffy white foam – the mass should increase in volume several times.
Then reduce the speed to a medium and thin stream pour warm chocolate mass.Finally, switch the mixer to the minimum speed and add one tablespoon of flour and baking powder. As soon as the mass becomes homogeneous, turn off the mixer.
In another bowl, whip the mascarpone with the remaining eggs, sugar and vanilla extract.
Grease the split form with butter and sprinkle with flour. Put on the bottom in three layers: half the chocolate mass, mascarpone filling and chocolate again. Smooth the surface of each layer before the next. To create a marble pattern make circular stains with a fork.
Put the form in the oven for an hour. Willingness to check with a toothpick: it should enter gently and go dry. Cool the finished cake, remove from the mold, sprinkle the surface with powdered sugar.
Decorate the cake with fresh berries and serve. Store at room temperature.