Preheat oven to 350°. Grease and line 8 (8 1/2-inch) round disposable cake pans with parchment paper.
Split vanilla bean lengthwise, and scrape out seeds. Whisk together vanilla bean seeds, sugar, and next 4 ingredients in a large bowl. Whisk together flour and next 3 ingredients in a second large bowl. Fold flour mixture into sugar mixture just until flour is incorporated.
Divide batter evenly (about 3/4 cup each) among prepared pans. Bake about 12 to 15 minutes or until cakes are light golden brown and centers spring back when touched. Let cool in pans on wire racks 10 minutes. Turn cakes out onto wire racks to cool completely. Carefully cut any domed tops from layers with a serrated knife.
Place 1 cake layer on cake stand; spread with about 1/3 cup Chocolate Ganache Icing using an offset spatula. Repeat with remaining layers and remaining icing. Coat the top and sides of the cake with a thin layer of icing; reserve remaining icing. Chill cake 1 hour.
Reheat reserved Chocolate Ganache Icing in a double boiler until smooth and pourable. Place cake over a wire rack on a rimmed baking pan. Starting at the center of the cake, pour icing in a slow, steady stream over top of cake, moving to outer edges and letting icing flow down the sides of the cake. Chill cake about 1 hour or until set. Carefully transfer cake to serving plate. Serve at room temperature.