Egg Sponge

Preparation

1. Line a buttered jelly-roll pan, 15 1/2 by 10 1/2 by 1 inches, with wax paper, butter the paper, and dust it with flour, knocking out the excess. In a saucepan melt the butter, add the flour, and cook the roux over moderately low heat, stirring, for 3 minutes. Add the milk in a stream, whisking, and simmer the mixture, whisking occasionally, for 5 minutes. Transfer the mixture to a large bowl and whisk in the yolks, 1 at a time, whisking well after each addition. In a bowl with an electric mixer beat the whites until they just hold stiff peaks, stir one third of them into the yolk mixture, and fold in the remaining whites gently but thoroughly. Spread the batter evenly in the prepared pan and bake it in the middle of a preheated 350°F. oven for 25 minutes, or until it is golden and firm to the touch. Cover the egg sponge with a sheet of buttered wax paper, buttered side down, and a kitchen towel, invert a baking sheet over the towel, and invert the egg sponge onto the baking sheet, removing the wax paper from the top carefully. Trim 1/4 inch from the short sides of the egg sponge.