Triple-Chocolate Cake with Chocolate-Peppermint Filling

PreparationFor filling: Place chocolate in medium bowl. Bring cream and corn syrup to simmer in small saucepan. Pour hot mixture over chocolate; add extract and let stand 1 minute. Whisk until mixture is smooth. Let filling stand at room temperature while cake is baking and cooling. For cake: Position rack in lowest third of oven and preheat to 350°F. Butter 9-inch-diameter cake pan with 2-inch-high sides. Line bottom with parchment paper. Butter parchment. Dust pan with flour. Whisk first 5 ingredients in medium bowl to blend. Using electric mixer, beat butter in large bowl until light and fluffy. Gradually beat in both sugars, then vanilla. Add eggs 1 at a time, beating well after each addition. Beat in dry ingredients alternately with buttermilk in 2 additions each. Mix in chocolate chips. Transfer batter to prepared pan. Bake cake until tester inserted into center comes out clean, about 1 hour 5 minutes. Cool cake in pan on rack 5 minutes. Turn out cake onto rack. Peel off parchment. Cool completely. Using electric mixer, beat filling until fluffy and lightened in color, about 30 seconds. Using serrated knife, cut cake horizontally in half. Place 1 layer, cut side up, on rack set over baking sheet. Spread filling over. Top with second layer, cut side down. Chill filled cake 20 minutes. Meanwhile, prepare glaze: Stir chocolate, butter, and corn syrup in heavy small saucepan over low heat until melted and smooth. Mix in extract. Cool glaze until just lukewarm but still pourable, stirring occasionally, about 20 minutes. Pour 1/2 cup glaze over center of cake. Spread over top and sides of cake. Chill until glaze sets, about 15 minutes. Pour remaining glaze over center of cake, then spread quickly over top and sides. Chill until glaze sets, about 1 hour. (Can be made 1 day ahead. Cover with cake dome; chill. Before continuing, let stand at room temperature until softened, about 4 hours.) Sprinkle candies around top edge of cake. Garnish with fresh mint leaves.

PreparationFor filling: Place chocolate in medium bowl. Bring cream and corn syrup to simmer in small saucepan. Pour hot mixture over chocolate; add extract and let stand 1 minute. Whisk until mixture is smooth. Let filling stand at room temperature while cake is baking and cooling. For cake: Position rack in lowest third of oven and preheat to 350°F. Butter 9-inch-diameter cake pan with 2-inch-high sides. Line bottom with parchment paper. Butter parchment. Dust pan with flour. Whisk first 5 ingredients in medium bowl to blend. Using electric mixer, beat butter in large bowl until light and fluffy. Gradually beat in both sugars, then vanilla. Add eggs 1 at a time, beating well after each addition. Beat in dry ingredients alternately with buttermilk in 2 additions each. Mix in chocolate chips. Transfer batter to prepared pan. Bake cake until tester inserted into center comes out clean, about 1 hour 5 minutes. Cool cake in pan on rack 5 minutes. Turn out cake onto rack. Peel off parchment. Cool completely. Using electric mixer, beat filling until fluffy and lightened in color, about 30 seconds. Using serrated knife, cut cake horizontally in half. Place 1 layer, cut side up, on rack set over baking sheet. Spread filling over. Top with second layer, cut side down. Chill filled cake 20 minutes. Meanwhile, prepare glaze: Stir chocolate, butter, and corn syrup in heavy small saucepan over low heat until melted and smooth. Mix in extract. Cool glaze until just lukewarm but still pourable, stirring occasionally, about 20 minutes. Pour 1/2 cup glaze over center of cake. Spread over top and sides of cake. Chill until glaze sets, about 15 minutes. Pour remaining glaze over center of cake, then spread quickly over top and sides. Chill until glaze sets, about 1 hour. (Can be made 1 day ahead. Cover with cake dome; chill. Before continuing, let stand at room temperature until softened, about 4 hours.) Sprinkle candies around top edge of cake. Garnish with fresh mint leaves.