Swiss Cheese & Mushroom Quiche

Ingredients

10 pie crust
1 ts butter
1 1/2 c onion
1/4 lb mushrooms
1/2 pinch salt
1/2 ts dry mustard
6 eggs
2 egg whites
1 1/2 c milk
2 tb flour
1 1/2 c packed swiss cheese

Instructions

warm, or at room temperature. ~-