Broccoli Souffle

2 tablespoons butter
2 tablespoons chopped onions
3 tablespoons all-purpose flour
2 cups milk
2 cups chopped broccoli, cooked
1 teaspoon salt
1 teaspoon pepper
1 teaspoon nutmeg
1 cup grated cheese (cheddar or Swiss)
6 eggs, separated

Brown onions in butter. Stir in flour; slowly add milk, stirring constantly. Stir in broccoli, seasonings and cheese and cook until thickened. Remove from heat and let cool.

Beat egg whites until stiff. Fold broccoli mixture into egg whites. Pour into casserole and bake at 350 degrees F for 45 minutes.