VANILLA SPONGE CAKE

1/2 tablespoon unsalted butter
1/4 cup all-purpose flour, as needed
1/4 cup cornstarch
2 large eggs, separated
1/2 teaspoon pure vanilla extract
6 tablespoons sugar
1 pinch salt

Heat oven to 350 degrees F. Butter two 6-inch-round layer-cake pans. Line pans with parchment paper, and butter again. Flour the pans, and set aside.

In a small bowl, sift together the flour and cornstarch; set aside.

In the bowl of an electric mixer fitted with the whisk attachment, beat the egg yolks, vanilla, and 4 tablespoons sugar on high speed, until thick and pale, about 5 minutes. Transfer the egg-yolk mixture to a large bowl.

Wash and dry the mixer bowl and the whisk attachment. Combine the egg whites and salt in the mixer bowl, and beat on medium speed, until whites hold soft peaks, about 1 1/2 minutes. With mixer running, slowly add the remaining 2 tablespoons sugar . Continue beating until stiff and glossy, about 1 minute.

Fold the egg-white mixture into the egg-yolk mixture. In three additions, fold the reserved flour mixture into this new mixture. Transfer the batter to the pans, and smooth the top with an offset spatula.

Bake until a cake tester inserted into middle comes out clean, 35 minutes. Transfer pans to a wire rack to cool; turn out the cakes, and wrap them in plastic wrap until ready to use.

Makes two (six-inch-round) layer cakes
Source: Martha Stewart Living magazine