You will need to make this recipe seven times for the Hexagonal Cake. If you have a six-quart mixer, you can mix two batches of batter at once. For best results, bake the tiers in 2-inch-high pans; if you use deeper pans, the layers will not be as moist. To reuse a pan for a second layer, remove the first layer and the parchment, and let the pan completely cool; then simply wipe the pan with a paper towel to remove any crumbs, and butter and flour again. You will need to make two each six-, nine-, and twelve-inch hexagonal layers, and two each eight- and twelve-inch round cake layers to cut into smaller hexagons.
Yield Makes 2 eight- or nine-inch cake layers
1 1/2 cups (3 sticks) unsalted butter plus more for pans
2 1/2 cups sifted cake flour (not self-rising), plus more for dusting
6 large eggs
1 3/4 cups sugar
Finely grated zest of 2 oranges
Preheat oven to 350 degrees. Butter cake pans. Line bottoms with parchment paper, being sure to cut them to fit neatly in pan; butter parchment, and dust with flour, tapping out excess.
Place butter in a large heatproof bowl set over simmering water, and beat until it reaches the consistency of soft mayonnaise.
In the bowl of an electric mixer fitted with the paddle attachment, beat eggs and sugar on low speed until combined. Raise speed to medium-high, and beat until mixture has doubled in volume, 5 to 6 minutes.
Add flour to egg mixture, 1/2 cup at a time, beating as little as possible after each addition to avoid deflating eggs. This entire step should take no more than 20 seconds.
Using a large rubber spatula, fold butter into the batter in three batches, being careful not to deflate batter. Very gently fold in grated orange zest.
Spoon batter into prepared pans, and tap pans against the counter to smooth tops. Bake until a cake tester inserted in center of each comes out clean, 20 to 40 minutes depending on size of pan. Remove from oven; let cakes cool in pans about 15 minutes, then turn out onto racks to cool completely before icing or storing. Cakes can be wrapped well in plastic and frozen up to 1 week; thaw completely at room temperature before using.