Prepare pie shell as pkg directs or use store bought. Melt margarine in skillet over medium high heat and sauté mushrooms and onion for 4 to 5 minutes. Add salt, paprika, and cayenne and set aside.
. Prick sides and bottom of pie shell with fork and bake in preheated 425 oven for 8 minutes. Remove from oven and reduce heat to 350.
Spread mushroom mixture over bottom of pie shell, distributing evenly. In small bowl, mix eggs and sour cream, blending well. Pour over mushrooms. Bake pie for 35 to 40 minute or until custard is firm. Remove from oven and let stand for 5 minutes before cutting into wedges. May be served as side dish or as main course. Serves 6