Swiss Chocolate Truffle Cake

Truffeltorte

An adaptation of the truffle cake from the famous Sprungli cake shop in Zurich. This dessert is easy to make in advance and, as it makes two cakes, one may be used immediately and the other refrigerated or frozen for later use.

Two 3 1/2 x 8-inch rectangular cakes

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Cake

6 ounces semisweet chocolate

12 tablespoons (1 1/2 sticks) unsalted butter

2/3 cup sugar

8 large eggs, separated

1 1/3 cups blanched or unblanched ground almonds

2/3 cup dry breadcrumbs

Filling

24 ounces (1 1/2 pounds) semisweet chocolate

2 cups heavy cream

3 tablespoons unsalted butter

3 tablespoons light corn syrup

Unsweetened cocoa powder for finishing

One 11 x 17-inch jelly-roll pan, buttered and lined with a sheet of parchment or wax paper

1. Set a rack in the middle level of the oven and preheat to 350 degrees.
2. To make the cake, cut the chocolate into fine pieces and place in a small bowl over hot water to melt, stirring occasionally. Set aside to cool. Beat the butter with 1/3 cup of the sugar until the mixture is soft and light, then beat in the chocolate, then the yolks, one at a time. In a small bowl, combine the almonds and crumbs and stir them in. In a clean, dry bowl with clean, dry beaters, beat the egg whites until they hold a very soft peak, then beat in the remaining 1/3 cup sugar in a slow stream. Continue to beat the whites until they hold a firm peak. Stir a quarter of the whites into the batter, then fold in the rest with a rubber spatula.
3. Spread the cake batter on the prepared pan and bake for about 20 minutes, or until firm. Slide the cake layer from the pan to a rack to cool.
4. To make the filling, cut up the chocolate into fine pieces and set aside. Combine the remaining ingredients in a pan and bring to a boil. Remove from the heat, add the chocolate, and allow to stand for 5 minutes. Whisk smooth and strain into a bowl. Refrigerate until thickened. Immediately before using the filling, whisk gently by hand to lighten slightly.
5. To assemble the cakes, cut the baked layer into 6 layers, each about 3 1/2 by 8 inches. Place 2 of the layers on 4 x 8 1/2-inch pieces of cardboard to make handling easier. Spread each with a thin layer of filling. Cover each with another layer, and cover those with the filling. Place the last layer on each cake and mask the sides with a thin layer of filling. Divide the remaining filling in half and place half on the top of each cake. Smooth the filling into a wedge shape on top of each cake; slant the short ends upward toward the center of the cake. Chill the cakes to set the filling, and dust very lightly with cocoa powder before serving.