Chestnuts are cooked, then peel and smash. Prepare the dough with hands smash the butter, sugar and flour two types. Add egg yolks, eggs and grated lemon rind. Everything is well kneaded, shaped ball and put in the fridge for half an hour. chestnut puree put in a saucepan with sugar and milk and boil for about 10 minutes. Add the chocolate, broken into pieces and stir until melted. Finally, add the mascarpone and allowed to cool. If necessary passaged. The dough is removed and divided into two parts - one slightly larger. Rolled out as with most cover the bottom and sides of the tart form. It is poured onto the filling. With the lower cover sheet is the form and the ends of the two parts of the dough is pinched. Top in several places is pricked with a fork. Heat the oven to 180C. Cake bake about 1 hour or until browned on the sheet. Cuts, once cooled down. Serve sprinkled with powdered sugar.