Layered White Butter Cake
Preheat oven to 350 degrees. Butter cake pans, and line with parchment paper; butter parchment. Dust with flour, tapping out excess; set aside. Whisk together flour, baking powder, and salt in a medium bowl; set aside. Stir together milk and vanilla in a small bowl; set aside.Advertisement
Put butter into the bowl of an electric mixer fitted with the paddle attachment; mix on medium speed until creamy, about 1 minute. Add sugar in a slow, steady stream; mix until pale and fluffy, about 3 minutes. Reduce speed to low. Add flour mixture in 3 batches, alternating with milk mixture; mix until just combined.
Put egg whites into the clean bowl of an electric mixer fitted with the whisk attachment; beat on medium-high speed until stiff peaks form. Using a rubber spatula, fold one-third of the egg whites into the batter. Gently fold in remaining egg whites in 2 batches. Divide batter among prepared pans; smooth tops with an offset spatula. Firmly tap pans on counter to eliminate any air bubbles.
Bake until a cake tester inserted into centers comes out clean. Let cool in pans on wire racks 15 minutes. Run a knife around edges to loosen; unmold onto racks, and remove parchment. Let cool completely. Cakes can be wrapped in plastic and frozen up to 1 month.
Batter amounts and cooking times for 2-inch-deep round pans
7-inch: 4 1/2 cups batter (13 1/2 cups total), 40 minutes; 9-inch: 9 cups batter (27 cups total), 40 minutes; 1 1-inch: 13 1/2 cups batter (40 1/2 cups), 40 minutes; 13-inch: 30 cups batter (90 cups total), 50 to 55 minutes; 15-inch: 39 cups batter (117 cups total), 50 to 55 minutes.
Buttercream and fondant amounts for each tier
7-inch: 1 cup buttercream per layer plus 1 cup for crumb coat (3 cups total), 2 pounds fondant; 9-inch: 1 1/2 cups buttercream per layer plus 1 1/2 cups for crumb coat (4 1/2 cups total), 2 1/2 pounds fondant; 11-inch: 3 cups buttercream per layer plus 2 cups for crumb coat (8 cups total), 3 1/4 pounds fondant; 13-inch: 6 cups buttercream per layer plus 4 1/2 cups for crumb coat (16 1/2 cups total), 3 3/4 pounds fondant; 15-inch: 7 cups buttercream per layer plus 6 cups for crumb coat (20 cups total), 5 pounds fondant.
Cut 3/16-inch-thick round foam boards into octagons for each tier. Trim each cake layer to 1 inch high. Tint buttercream, and spread on 2 cake layers (see note above for amounts). Stack layers on corresponding octagonal foam board, placing the plain layer on top. Refrigerate 30 minutes. Invert tier, and cut into an octagon along edges of foam board as shown above; reinvert. Coat tiers with buttercream; refrigerate 30 minutes. Tint fondant. Smooth fondant over tiers. Before stacking the tiers, add supports: Insert dowels, trimmed to the height of the tier, into all but top tier, arranging 1 in center and the rest evenly spaced, about 2 inches apart and 2 inches from edge. Stack tiers, inserting fondant-covered octagonal cake risers between tiers. Decorate as desired.