I know this originally Hungarian cake only in its Viennese form. In Vienna, it is made from two thin layers of chocolate cake with a whipped chocolate cream filling and a shiny chocolate glaze—definitely a dessert for an important party. The good news is that it can be made entirely in advance. Do wait to cut it until right before serving, however, or the cake layers will dry out.
- 6 ounces semisweet chocolate
- 6 large eggs, separated
- Pinch of salt
- ½ cup sugar
- ¼ cup all-purpose flour (spoon flour into dry-measure cup and level off)
- 1½ cups heavy whipping cream
- 2 tablespoons light corn syrup
- 2 tablespoons butter
- 16 ounces semisweet chocolate, cut into ¼-inch pieces
- ½ cup heavy whipping cream
- 2 tablespoons light corn syrup
- 6 ounces semisweet chocolate, cut into ¼-inch pieces
- One 12 × 18-inch jelly-roll pan, bottom and sides buttered and lined with buttered parchment or foil
1. Set a rack in the middle level of the oven and preheat to 350 degrees.
2. Bring a small pan of water to a boil and turn off the heat. Combine the chocolate and ¼ cup water in a heatproof bowl and place over the pot of water. Stir until chocolate is melted and smooth.
3. For the cake batter, put the 6 yolks in the bowl of an electric mixer and whisk in ¼ cup of the sugar by hand. Place the bowl on the mixer fitted with the whisk attachment and whip the mixture on medium-high speed until the yolks and sugar are light and thickened. If you have only one mixer bowl and one whisk, scrape the yolk mixture into a medium mixing bowl. Wash the bowl and whisk in hot, soapy water, then rinse and dry them.
4. Put the 6 egg whites and salt in the clean, dry mixer bowl. Place on the mixer fitted with the whisk attachment, and whip the whites on medium speed until they are white, opaque, and beginning to hold a very soft peak. Increase the speed to medium high and whip in the remaining ¼ cup sugar in a stream. Continue whipping the whites until they hold a firm peak.
5. Stir the melted chocolate into the yolk mixture, immediately followed by about a fourth of the whipped egg whites. Sift and fold in the flour, and then fold in the remaining egg whites.
6. Scrape the batter onto the prepared pan and use a medium offset spatula to spread the batter evenly.
7. Bake the cake layer until it is risen (it will not rise very high) and firm when pressed with a fingertip, about 15 to 20 minutes. Slide the paper from the pan to a rack to cool the cake.
8. For the filling, bring the cream and corn syrup to a boil in a large saucepan, stirring occasionally to make sure that the corn syrup doesn’t fall to the bottom and burn. Remove the pan from the heat and add the butter and chocolate. Gently shake the pan to make sure that the butter and chocolate are completely submerged, then wait 2 minutes for them to melt. Whisk the filling smooth and pour it into a bowl. Refrigerate the filling until it is about 80 degrees, or until it is of spreading consistency. Don’t leave the filling in the refrigerator too long, or it will become too hard to whip.
9. To assemble the cake, slide the paper with the cake still stuck to it onto a cutting board. Cut through both the paper and the cake with a sharp serrated knife to make two 12 × 9-inch rectangles. Slide one off the cutting board. Run a long, thin knife or spatula between the paper and the cake that remains on the cutting board to loosen it, but leave the paper under the cake. (This will make the cubes of finished cake easier to remove later on.)
10. Scrape the cooled filling into the bowl of an electric mixer and beat it with the paddle on medium speed until it is lightened to a milk chocolate color. Don’t overheat, or the filling will separate.
11. Immediately use a medium offset spatula to spread the whipped filling evenly over the cake layer on the cutting board.
12. Invert the remaining cake layer, still stuck to the paper for easy handling, to a cookie sheet with no sides or to a stiff rectangular piece of cardboard. Gently slide the cake layer into place over the filling. Carefully peel off the paper.
13. Place a stiff cardboard or cookie sheet on the cake and gently press to make sure the top layer of cake adheres well to the filling.
14. Refrigerate the cake while preparing the glaze.
15. For the glaze, bring the cream and corn syrup to a simmer in a medium saucepan, stirring occasionally. Remove the pan from the heat and add the chocolate. Gently shake the pan to make sure that all the chocolate is submerged, then wait 2 minutes for it to melt. Whisk the glaze just until smooth. Avoid whisking too much, or the glaze will be riddled with bubbles. Let the glaze cool until it is just slightly warm to the touch, about 100 to 105 degrees.
16. After the glaze has cooled, remove the cake from the refrigerator and pour the glaze over it. Quickly spread the glaze evenly with a medium offset spatula. Don’t worry about any glaze that drips down the sides of the cake; it will be trimmed away later.
17. Refrigerate the cake again for at least 1 hour, or up to 24 hours, to set the glaze.
18. Rinse a long, sharp serrated knife in hot water, then wipe it dry with a cloth. Use the knife to trim the sides of the cake evenly, rinsing and wiping after each cut. Cut the cake into 2-inch squares. Lift the cubes of cake off the paper with an offset cake server or spatula and line them up symmetrically on a platter. Serve alone or with a little unsweetened whipped cream.
Serving size is one square.