Yield: 6-8 servings
Line a 9-inch pie plate with pastry. In a skillet, saute mushrooms and onion in butter; drain.
Arrange half of the cheese slices in the crust. Top with half of the mushroom mixture. Repeat the layers. Place remaining pastry over filling; trim and seal edges.
Cut slits in the top. Bake at 350 degrees for 45-50 minutes or until golden brown. Let stand for 10 minutes. Cut into wedges.
Please note that some ingredients and brands may not be available in every store.