Chocolate Chestnut Cake

For the filling and glaze: Coarsely chop the chocolate. Heat 200 grams (approximately 1 cup) of the cream in a saucepan, remove from heat, add 200 grams (approximately 8 ounces) of the chopped chocolate and stir until melted. Cover and refrigerate overnight.

For the dough: Chop the chocolate coarsely, place in a saucepan with the butter and 75 ml (approximately 1/3 cup) of water and melt over low heat. Stir in the sugar, cool briefly, then stir in the cream and vanilla.

Preheat the oven to 170°C (approximately 350°F). Line a baking sheet with parchment paper.

Finely grind the hazelnuts and chestnuts in a spice grinder and transfer to a bowl. Stir the flour, cocoa, baking powder and a pinch of salt into the chocolate mixture. Add the eggs one at a time, stirring well after each addition. Stir in the hazelnuts and chestnuts. Pat the dough out on the baking sheet to a  25 x 30 cm (approximately 10 x 12-inch) rectangle. Bake until a toothpick inserted in the center comes out clean, 35 to 40 minutes. Let cool on a wire rack.

Cut an 18 cm (approximately 7-inch) circle and two 11 x 11 cm (approximately 4 1/2 x 4 1/2-inch) squares and two 9 x 9 cm (approximately 4 x 4 -inch) out of the chocolate cake.

Cut the circle and the squares in half crosswise. Beat the cold chocolate mixture until frothy. Spread the chocolate-hazelnut mixture over the pieces of cake and stack together.