Chocolate Cake with Coffee Sauce
3/4 cup heavy (whipping) cream
2 tablespoons instant coffee powder
4 ounces bittersweet chocolate, chopped
2 ounces unsalted butter
1 teaspoon vanilla extract
1/4 cup water
4 ounces unsalted butter, melted
scant cup confectioners' sugar
scant cup cake flour, sifted
3 egg whites
1/2 vanilla bean
3/8 cup cake flour
1 1/2 cups almond flour
12 ounces bittersweet chocolate, chopped
5 ounces unsalted butter
6 egg yolks
6 egg whites
1 cup sugar
cocoa for dusting
To make the coffee sauce: Warm the cream in a saucepan over medium heat. Stir in the coffee powder. When blended, take off the heat and stir in the chocolate. When the chocolate has melted, whisk in the butter and vanilla, then whisk in the water. Pour into small 1-inch molds and freeze until hard, about 2 hours.
To make the vanilla petals: Preheat the oven to 350 F. Line a baking sheet with parchment paper or silicone liner. Make a stencil: cut 6-inch-by-1-inch petal shapes out of a piece of heavy plastic or thin cardboard. Stir all the ingredients except the vanilla bean together until smooth. With the point of a sharp knife, scrape the seeds from the vanilla bean into the mixture; discard the husk or place in a jar of sugar to scent the sugar for other use. Cover the bowl with plastic wrap and refrigerate for 30 minutes. Lay the stencil on the prepared pan and spread the pastry batter over it with a spatula; lift off to leave a petal shape. Repeat to form petals. Bake for 10 minutes. Remove from oven and lift a petal with a spatula; place it over a large-diameter curved object, like a coffee can, to cool. Repeat with remaining petals; if they become too cool to bend, return them briefly to the oven to warm. Let the petals cool, then set aside.
To make the cake: Sift the cake flour and almond flour together. Melt the chocolate and butter together in the top of a double boiler over barely simmering water. Whisk in the egg yolks and remove from the heat. In a deep bowl, beat the egg whites until foamy, then slowly add the sugar while continuing to beat until the whites stand in firm peaks. Fold a large spoonful of the beaten egg whites into the chocolate mixture, then gently fold in the remaining whites. Fold in the flour mixture.
Preheat the oven to 350 F. Place heat-proof ring molds on a baking sheet lined with parchment paper or a silicone liner. Line the molds with parchment paper that has been lightly buttered and dusted with cocoa powder, facing the cocoa powder side in. Fill the molds with 1 inch of chocolate cake batter. Place a frozen coffee mold in the center of each.
Fill the molds the rest of the way with cake batter. Bake 14 minutes, until the cake is firm to the touch.
To serve: Place a warm chocolate cake mold in the center of each plate. Slip the wide ends of the curved petals under the molds all the way around, dividing the molds between the plates. Lift the mold off the chocolate cake and dust the cake with cocoa powder.