Preparation Put oven rack in middle position and preheat oven to 375°F. Generously butter a 2 1/2- to 3-quart soufflé dish (3 to 4 inches deep) or other deep baking dish. Heat milk in a 2-quart heavy saucepan over moderate heat until hot but not boiling, then add cornmeal in a stream, whisking, and cook, whisking, until very thick and smooth, about 2 minutes. Transfer to a large bowl and stir in butter, salt, baking powder, and yolks, then cool to lukewarm. Beat egg whites with a pinch of salt in another bowl using an electric mixer until they just hold stiff peaks. Stir one fourth of whites into cornmeal mixture to lighten, then fold in remaining whites gently but thoroughly. Spoon batter into baking dish and bake until golden brown and puffed, 45 to 50 minutes. Serve immediately.
Preparation Put oven rack in middle position and preheat oven to 375°F. Generously butter a 2 1/2- to 3-quart soufflé dish (3 to 4 inches deep) or other deep baking dish. Heat milk in a 2-quart heavy saucepan over moderate heat until hot but not boiling, then add cornmeal in a stream, whisking, and cook, whisking, until very thick and smooth, about 2 minutes. Transfer to a large bowl and stir in butter, salt, baking powder, and yolks, then cool to lukewarm. Beat egg whites with a pinch of salt in another bowl using an electric mixer until they just hold stiff peaks. Stir one fourth of whites into cornmeal mixture to lighten, then fold in remaining whites gently but thoroughly. Spoon batter into baking dish and bake until golden brown and puffed, 45 to 50 minutes. Serve immediately.