Ingredients

12 large egg whites (about 1-2/3 cups)1 cup cake flour1-1/2 cups sugar, divided 1 vanilla bean (see Editor’s Note) or 1 teaspoon vanilla extract1/2 teaspoon cream of tartar1/4 teaspoon saltFILLING:1 cup (6 ounces) 60% cacao bittersweet chocolate baking chips1 cup heavy whipping cream, divided1 tablespoon amaretto1 tablespoon sugarGLAZE:1 cup (6 ounces) 60% cacao bittersweet chocolate baking chips1/2 cup heavy whipping cream1 tablespoon sugar2 tablespoons amaretto1/4 cup sliced almonds, toasted

Preparation

Place egg whites in a large bowl; let stand at room temperature 30 minutes.

Preheat oven to 325°. In a small bowl, mix flour and 3/4 cup sugar until blended.

Add seeds from vanilla bean (or extract if using), cream of tartar and salt to egg whites. Beat on medium speed until soft peaks form. Gradually add remaining 3/4 cup sugar, 1 tablespoon at a time, beating on high after each addition until sugar is dissolved. Continue beating until soft glossy peaks form. Gradually fold in flour mixture, about 1/2 cup at a time.

Gently transfer batter to an ungreased 10-in. tube pan. Cut through batter with a knife to remove air pockets. Bake on lowest oven rack 45-55 minutes or until top springs back when lightly touched. Immediately invert pan; cool completely in pan, about 1-1/2 hours.

For filling, in a large microwave-safe bowl, combine baking chips, 1/4 cup cream and amaretto; microwave on high for 60-90 seconds or until chocolate is melted, stirring every 30 seconds. Continue stirring until mixture is smooth and glossy; cool to lukewarm (90°), about 25-30 minutes.

Meanwhile, run a knife around sides and center tube of pan. Remove cake to a serving plate. Using a serrated knife, cut a 1-in. slice off top of cake. Hollow out remaining cake, leaving a 1-in.-thick shell (save removed cake for another use). In a small bowl, beat remaining 3/4 cup cream until it begins to thicken. Add sugar; beat until soft peaks form.

Fold whipped cream into lukewarm chocolate; spoon into tunnel. Replace cake top. Refrigerate, covered, at least 4 hours or overnight.

For glaze, place baking chips in a small bowl. In a small saucepan, combine cream and sugar; bring just to a boil, stirring to dissolve sugar. Pour over baking chips; stir with a whisk until smooth. Stir in amaretto. Cool slightly, about 15 minutes.

Unwrap cake; pour glaze over top, allowing some to drip down sides. Sprinkle with almonds.