1 tbsp. butter
2 tbsp. flour
2/3 c. buttermilk
3 eggs, separated
1/2 c. grated Cheddar cheese
1/8 tsp. dry mustard
1 tsp. dried minced onion
Dash of pepper
1/2 tsp. salt
Pinch of cream of tartar

Melt butter; stir in flour. Add buttermilk; stirring constantly until mixture comes to a boil. Beat egg yolks. Add cheese and yolks; cook stirring until cheese melts and mixture is smooth. Add mustard, onion and pepper. Cool.

Beat egg whites, salt and cream of tartar until stiff. Fold into cheese mixture. Spoon into 1 quart casserole which has been lightly sprayed with cooking spray. Bake at 350 degrees for 25 minutes. Serve immediately.