Butter and line with paper a
For the chocolate walnut cake batter, cut the chocolate finely and place in a small bowl over hot water to melt, stirring occasionally. Beat the butter with half the sugar until soft and light, either by hand, with a hand mixer set at medium speed, or in a heavy-duty mixer fitted with the paddle. Beat in the chocolate, then the egg yolks, one at a time. Combine the walnuts and flour and stir into the butter-and-chocolate mixture. In a clean, dry bowl, whip the egg whites until they hold a very soft peak, and whip in the remaining sugar in a slow stream. Whip the whites until they hold a soft peak. Stir one-fourth of the whites into the batter, then fold in the rest with a rubber spatula. Pour the batter into the prepared pan and bake at 350 degrees for about 35 minutes. Unmold the cake onto a rack to cool.
For the syrup, bring the sugar and water to a boil in a small saucepan. Cool and stir in the rum.
For the chocolate filling, cut the chocolate finely and set aside. Bring the cream and corn syrup to a boil in a saucepan and remove from the heat. Stir in the chocolate and allow to stand about 2 minutes so that the chocolate melts. Whisk smooth, whisk in the butter and rum, and scrape into a bowl. Cool at room temperature or in the refrigerator until set and thickened.
To assemble the torta, trim the top of the cooled cake layer so it is even and slice into 2 layers. Place one layer on a cardboard disk and moisten with some of the syrup. Beat the chocolate filling, either with a hand mixer set at medium speed or in a heavy-duty mixer fitted with the paddle, for about 1 minute, until it is lightened. Spread one-fourth of the filling on the layer. Top with the other layer and moisten with more syrup. Use another fourth of the filling to cover the top and sides of the cake.
Use the remaining filling to decorate the torta: with a pastry bag fitted with a small star tube, such as Ateco #2, pipe a series of vertical lines, touching, around the sides of the torta. Pipe a perpendicular lattice of 5 lines in each direction on the top of the torta. Then pipe a series of rosettes at the top border. Fill each opening in the lattice with a walnut half.
Serve the torta at room temperature. Store leftovers in the refrigerator.
Walnut halves for finishing
© 1990 Nick Malgieri. All rights reserved.