Let egg whites stand at room temperature in a very large bowl for 30 minutes. Grease and lightly flour a 9-inch springform pan. Set aside.
Melt chocolate and butter in a medium saucepan over low heat; cool. Stir egg yolks and vanilla into the cooled chocolate mixture. Set mixture aside.
Beat egg whites with an electric mixer on medium to high speed until soft peaks form (tips curl). Gradually add sugar, about 1 tablespoon at a time, beating about 4 minutes or until stiff peaks form (tips stand straight).
Fold about 1 cup of the egg white mixture into chocolate mixture. Fold chocolate mixture into remaining egg white mixture. Sift about one-third of the flour over the egg mixture; gently fold in. (If the bowl is too full, transfer mixture to a larger bowl.) Repeat twice, sifting and folding in one-third of the flour at a time.
Spread batter into the prepared pan. Bake in a 350 degree F oven for 30 to 35 minutes or until a wooden toothpick inserted near the center comes out clean. Completely cool cake in the pan on a wire rack. Remove sides of pan. Brush crumbs from edges of cake. (Top crust will be slightly flaky.) Remove bottom of pan from cake.
Heat preserves in a small saucepan until melted. Press apricot preserves through a sieve; cool slightly.
To assemble, cut cake horizontally into two even layers. Place the bottom layer on a large serving plate. Spread the preserves on top of the cake layer on plate. Top with the second cake layer. Pour Chocolate Glaze over torte, spreading as necessary to glaze top and sides completely. Let torte stand at room temperature at least 1 hour before serving. If desired, top with chocolate curls; garnish with edible flowers. Makes 12 servings.
Cut up semisweet or bittersweet chocolate. Heat chocolate and butter or margarine in a saucepan over low heat just until melted, stirring occasionally; set aside. Bring whipping cream and light corn syrup to a gentle boil in a heavy small saucepan. Reduce heat and simmer for 2 minutes. Remove from heat. Stir in chocolate mixture. Cool to room temperature.