Walnut Torte with Walnut-Custard Buttercream

Diostorte

Preparation info

  • Difficulty

    Medium

  • Makes

    12

    servings

Appears in

Ground walnuts give this Hungarian cake the dense texture that Americans think of when they hear the word “torte.” The catch is that the nuts for the cake must be ground by hand with a rotary nut grinder. Don’t use a food processor, as it doesn’t give the nuts the requisite fluffiness. The frosting is based on a custard, which gives it a rich creaminess that is hard to duplicate or surpass with other methods. Thanks to Ella Szabo for her fine recipe.

Ingredients

Cake

  • cup dried unflavored bread crumbs, for the pan
  • 1 cup walnuts
  • 1 cup all-purpose flour
  • 7 large eggs, at room temperature
  • ¾ cup granulated sugar

Icing

  • 2 cups chopped walnuts
  • cups confectioners’ sugar
  • 1 cup milk
  • 2 tablespoons cornstarch
  • 2 large egg yolks
  • 2 tablespoons golden rum
  • 1 teaspoon vanilla extract
  • cups (3 sticks) unsalted butter, at cool room temperature

Assembly

  • ½ cup finely chopped walnuts, for garnish
  • 12 walnut halves, for garnish

Method

  1. To make the cake: Position a rack in the center of the oven and heat to 350°F. Lightly butter a 9-inch springform pan. Dust with bread crumbs and tap out the excess crumbs. Line the bottom of the pan with a round of parchment or wax paper.
  2. Grind the nuts in a rotary nut grinder fitted with the fine grating drum. Transfer to a bowl and mix with the flour.
  3. Beat the eggs and sugar in the bowl of a heavy-duty electric mixer at high speed until the mixture is very thick and forms a slowly dissolving ribbon when the beaters are lifted a few inches, about 5 minutes.
  4. In two additions, fold in the walnut mixture with a large balloon whisk or rubber spatula. Spread evenly in the pan.
  5. Bake until a toothpick inserted in the center of the cake comes out clean, about 35 minutes. Cool in the pan on a wire rack for 5 minutes. Remove the sides of the pan, and invert the cake onto the rack. Remove the paper. Reverse onto another rack and cool completely.
  6. To make the icing: Process the walnuts and confectioners’ sugar in a food processor fitted with the metal blade until the walnuts are very finely chopped, almost a powder.
  7. Pour the milk into a medium saucepan. Sprinkle in the cornstarch, and whisk to dissolve. Whisk in the yolks. Cook over medium-low heat, whisking constantly, until the sauce is boiling and as thick as pudding. The sauce must come to a full boil; the cornstarch will prevent the yolks from curdling. Strain the custard into a medium bowl set in a larger bowl of ice water. Stir in the rum and vanilla. Let stand until cool, stirring occasionally.
  8. Transfer the custard to the bowl of a heavy-duty standing mixer with the whisk attached and beat until smooth, about 1 minute. On medium speed, one tablespoon at a time, beat in the butter, occasionally increasing the speed to high for about 10 seconds to ensure smooth blending. Beat in the walnut-confectioners’ sugar mixture. If the icing is too warm to spread, place the bowl in a larger bowl of ice water and let stand, stirring occasionally, until chilled and spreadable.
  9. To assemble: Transfer about ¾ of the icing to a pastry bag fitted with a 9/16-inch-wide French star tip, such as Ateco Number 865. Using a long serrated knife, horizontally slice the cake into 2 equal layers. Place the bottom layer on an 8-inch cardboard round or a serving plate. Spread with about 1 cup of the remaining icing. Top with the other layer, and frost the top and sides of the cake with the remaining icing. Press the chopped walnuts onto the side of the cake. Pipe twelve rosettes on top of the cake and place a walnut half on each. Refrigerate under a cake dome until 1 hour before serving.

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