Mushroom Soufflé

2 cups fresh mushrooms
1 small onion
2 tablespoons margarine
2 tablespoons flour
2/3 cup milk
4 egg yolks
4 egg whites
1/4 cup grated Parmesan cheese

Combine flour and margarine over low heat; add milk, cook until thickened, raising heat slightly if necessary.
Sauté’ and add the mushrooms and onions. Cool.
Beat and fold in egg yolks.
Fold mixture into stiffly beaten egg whites.
Bake 30 minutes at 375° F.