Ingredients

  • 1 1/4 cups cake flour (not self-rising) plus additional for dusting
  • 1 1/2 cups granulated sugar
  • 6 large eggs, separated
  • 2 tablespoons warm water
  • 1 teaspoon vanilla
  • 4 ounces hazelnuts (1 cup)
  • 3 cups chilled heavy cream
  • 1/2 cup confectioners sugar
  • 1/3 cup Strega liqueur
  • 2 ounces fine-quality bittersweet chocolate, shaved

Method

  • Preheat oven to 350F and butter a 10- by 2-inch round cake pan or 10-inch springform pan.
  • Line bottom with a round of wax paper.
  • Butter paper.
  • Dust pan with flour, knocking out excess.
  • Sift together 1 1/4 cups flour and 2 tablespoons sugar.
  • Beat together yolks, 1 cups sugar, and warm water with an electric mixer until thick, pale, and doubled in volume, 5 to 7 minutes.
  • Beat in vanilla, then gradually beat in flour on low speed until incorporated.
  • Beat whites in a large bowl with cleaned beaters until they hold soft peaks.
  • Add remaining 2 tablespoons sugar.
  • Beat until whites just hold stiff peaks.
  • Fold one third of whites into yolk mixture gently but thoroughly.
  • Fold in remaining whites.
  • Pour batter into cake pan and bake in middle of oven until pale golden and a tester inserted 1 inch from center comes out with a few crumbs adhering, 30 to 40 minutes.
  • Turn off oven and cool cake in oven with door ajar 30 minutes.
  • Run a knife around edge of cake and invert onto a rack.
  • Remove pan and paper, then cool completely.
  • Preheat oven to 350F.
  • Toast hazelnuts in a baking pan in middle of oven until golden and skins are blistered, 10 to 15 minutes.
  • Wrap nuts in a kitchen towel and let them steam 1 minute.
  • Rub nuts in towel to remove loose skins (don't worry about skins that dont come off).
  • Grind warm nuts in a food processor until they form a paste and chill until cold.
  • Beat 2 cups cream with 5 tablespoons confectioners sugar with electric mixer until it holds stiff peaks.
  • Chill until ready to assemble cake.
  • Beat remaining cup cream with remaining 3 tablespoons confectioners sugar until cream just holds stiff peaks, then beat in cold hazelnut paste.
  • Chill hazelnut filling until ready to assemble cake.
  • Trim off any loose, crusty pieces from top and sides of cake.
  • Halve cake horizontally with a long serrated knife and remove top half.
  • Brush bottom half with two thirds of Strega, then spread all of hazelnut filling over it.
  • Cover with top half of cake and brush with remaining Strega.
  • Frost side and top of cake with whipped cream.
  • Freeze cake until firm, at least 3 hours.
  • Let cake stand at room temperature 1 hour before serving, then sprinkle top with chocolate shavings.