Allow the egg yolks and egg whites to stand at room temperature for 30 minutes.

For cheese sauce, in a medium saucepan melt butter; stir in flour, dry mustard, and cayenne pepper. Add milk all at once. Cook and stir over medium heat until thickened and bubbly. Remove from heat. Add cheese, a little at a time, stirring until melted. In a medium bowl beat egg yolks with a fork until combined. Slowly add cheese sauce to egg yolks, stirring constantly. Cool slightly.

In a large mixing bowl beat egg whites with an electric mixer on medium to high speed until stiff peaks form (tips stand straight). Gently fold about 1 cup of the stiffly beaten egg whites into cheese sauce.

Gradually pour cheese sauce over remaining stiffly beaten egg whites, folding to combine. Pour into an ungreased 2-quart souffle dish.

Bake in a 350 degree F oven for about 40 minutes or until a knife inserted near center comes out clean. Serve immediately. Makes 4 servings.