Brush butter and flour mixture over the inside of 2 cake pans, 10 inches (25 cm) in diameter, or coat the pans with cake pan spray. Reserve.
Place the eggs, sugar, and salt in mixer bowl. Heat over simmering water to about 110°F(43°C), whipping continuously. Remove from the heat and whip at high speed until the mixture has cooled, is light and fluffy, and has reached its maximum volume.
Sift the flour and the cornstarch together and fold into the batter by hand (Figures 9-2 and 9-3). Fold in the melted butter. Divide the batter between the prepared pans.
Bake immediately at 400°F(205°C) for approximately 15 minutes. Let the sponges cool before removing them from the pans.