01.  Preheat the oven to 356°F and grease a round cake pan.

02.  Melt the chocolate and butter in a double boiler. Set aside.

03.  Crush the chestnuts until they are finely ground.

04.  In a bowl, beat the eggs and sugar until you get a light cream.

05.  Add the melted chocolate and butter mixture and mix well.

06.  Stir in the chestnut flour, all-purpose flour, baking powder, and a pinch of salt. Mix until you have a homogeneous batter.

07.  Pour the batter into the cake pan and bake for about 30-35 minutes, or until a toothpick comes out clean.

08.  Allow it to cool before serving.