1.  To make the torte: Position a rack in the centre of the oven and heat to 400°F. Lightly butter a 9-inch springform pan and line the bottom with a round of parchment or wax paper. Dust the sides of the pan with flour and tap out the excess.
2. In the top part of a double boiler over very hot, but not simmering, water, or in a microwave at medium power, melt the chocolate. Remove from the heat or the oven, and let stand, stirring often, until cool.
3. Beat the butter in the bowl of a heavy-duty standing mixer fitted with the paddle blade on medium-high speed until smooth, about 1 minute. At low speed, beat in the confectioners’ sugar. Return the speed to medium-high and beat until light in colour and texture, about 2 minutes. Beat in the egg yolks, one at a time, scraping down the sides of the bowl. Beat in the chocolate and vanilla.
4. Beat the egg whites and granulated sugar in a large bowl with a handheld electric mixer on high speed just until they form soft, shiny peaks. Do not overbeat. Stir about one-fourth of the beaten whites into the chocolate mixture to lighten it, then fold in the remaining whites, leaving a few visible wisps of whites. Sift half of the flour over the chocolate mixture, and fold in with a large balloon whisk or rubber spatula. Repeat with the remaining flour.
5. Spread evenly in the pan. Bake until a toothpick inserted in the centre comes out clean, about 45 minutes. (The cake will dome in the centre.) Cool on a wire rack for 10 minutes. Remove the sides of the pan, and invert the cake onto the rack. Remove the paper and reinvert it on another rack to turn the right side up. Cool completely.

To assemble:

1. Using a long serrated knife, trim the top of the cake to make it level. Cut the cake horizontally into two equal layers. Place one cake layer on an 8-inch cardboard round. Brush the top of the cake layer with the apricot glaze. Place the second cake layer on top and brush again. Brush the top and sides of the cake with the remaining glaze. Transfer the cake to a wire rack placed over a jelly-roll pan lined with waxed paper. Let cool until the glaze is set.
2. Make the chocolate glaze (it must be freshly made and warm). Pour all of the warm chocolate glaze on top of the cake. Using a metal offset spatula, gently smooth the glaze over the cake, allowing it to run down the sides, being sure that the glaze completely coats the cake (patch any bare spots with the spatula and the icing that has dripped). Cool until the glaze is barely set, then transfer the cake to a serving plate. Refrigerate until the glaze is completely set, at least 1 hour. Remove the cake from the refrigerator about 1 hour before serving.
3. To serve, slice with a sharp knife dipped into hot water. Serve with a large dollop of whipped cream on the side.