Remove from heat. Add cheese and stir until melted. Cover and set aside. Melt remaining 2 tablespoons butter in large skillet. Saute remaining mushrooms and onions until all liquid has evaporated. Add eggs and continue cooking and stirring until mixture is just set. Fold eggs into cheese sauce. Pour into 12 x 7 1/2 x 2 inch baking pan.

Sprinkle bread crumbs over mixture. Cover and refrigerate overnight. Bake uncovered, in moderate oven (350°F) for 20 to 25 minutes or until heated through.

Makes 6 to 8 servings.