In the microwave, sauté the onions, peppers, and mushrooms in butter for 1 1/2 minutes on high in a small bowl. Combine the egg, sour cream, bacon, cheeses, vegetables, salt and pepper; set aside. Roll out the two unbaked pie crusts. With a round cookie cutter, cut out circles of dough and line small mini-muffin tins (or a tart pans) sprayed with nonstick spray. Spoon the egg mixture into the pie crust lined mini-muffin tins. Bake at 350 degrees for 20-25 minutes. Serve while hot.