Heavenly Chocolate Trifle

Cake12 ounces bittersweet (not unsweetened) or semisweet chocolate, chopped 3/4 cup (1 1/2 sticks) unsalted butter, cut into pieces6 large eggs, separated12 tablespoons sugar, divided2 tablespoons vanilla extractSauce4 ounces German chocolate, coarsely chopped 1/2 ounce unsweetened chocolate, coarsely chopped8 tablespoons (1 stick) butter, cut into pieces3 cups powdered sugar1 can (12 ounces) evaporated milk 1/4 teaspoons vanilla extractFillings2 1/2 cups heavy cream 1/3 cup sugar3 toffee candy bars, broken into small piecesHeat oven to 350 degrees. Butter 9-inch cake or spring form pan and line bottom with parchment paper.For the cake: Stir chocolate and butter in heavy medium saucepan over low heat until melted and smooth. Remove from heat; cool to lukewarm, stirring often.Using electric mixer, beat egg yolks and 6 tablespoons sugar in large bowl until mixture is very thick and pale, about 3 minutes. Fold lukewarm chocolate mixture into yolk mixture, then fold in vanilla extract. Using clean dry beaters, beat egg whites in another large bowl until soft peaks form. Gradually add remaining 6 tablespoons sugar, beating until medium-firm peaks form. Fold whites into chocolate mixture in 3 additions. Pour batter into prepared pan. Bake cake until top is puffed and cracked and tester inserted into center comes out with some moist crumbs attached, about 50 minutes. Cool cake in pan on rack (cake will fall).For the sauce: Melt the German chocolate and unsweetened chocolate with the butter in a saucepan over low heat. Stir in the powdered sugar, alternating with evaporated milk and blending well. Stirring constantly, bring the mixture to a simmer over medium heat. Simmer until the mixture becomes thick and creamy, about 8 minutes. Stir in the vanilla.Beat whipping cream with the sugar until soft peaks form.To assemble: Remove cake from pan and slice into 1-inch thick pieces. Line the bottom of a large glass bowl with a single layer of cake. Pour one-fourth of the fudge sauce over the cake, top with one-fourth of the candy bar bits then one-third of the whipped cream. Repeat layering 2 more times ending with fudge sauce and candy bits. Refrigerate until ready to serve.Serves 12.Cook's notes: Assemble the trifle shortly before serving or it will get soggy. Sauce can be made in advance; refrigerate until ready to use. You may use a chocolate cake mix and prepared fudge sauce.Nutrition values per serving: 915 calories, 65 g fat (39 g saturated), 80 g carbohydrates, 1 g fiber, 10 g protein, 263 mg cholesterol, 126 mg sodium.