Directions

• Step 1
  Measure enough foil to go around a 2-quart soufflé dish plus a 2- to 3" overlap. Fold foil into thirds lengthwise. Lightly butter one side. With the buttered side in, position the foil around the dish, letting the collar extend 2" above the top of the dish; fasten with tape. Set aside.
• Step 2
  Melt the butter in a saucepan; stir in the flour, salt, and cayenne. Add milk all at once. Cook and stir till thickened and bubbly. Cook and stir 1 to 2 minutes more. Remove from heat. Add the cheeses, stirring until cheese is melted. Beat egg yolks until thick. Slowly add cheese mixture to the egg yolks, stirring constantly. Cool slightly.
• Step 3
  Preheat the oven to 300°F. Using clean beaters, beat egg whites until stiff peaks form. Gradually pour the cheese-yolk mixture over the beaten whites, folding to combine. Pour into the ungreased soufflé dish. Bake about 1½ hours or until a knife inserted in the soufflé comes out clean. Gently peel off the collar. Serve immediately.