2 tbsp. butter
3 med. sweet spanish onions, sliced
8 oz. fresh mushrooms, sliced
1 c. (4 oz.) shredded Swiss cheese
1 can (5 oz.) evaporated milk
1 can (10 3/4 oz) condensed cream of mushroom soup, undiluted.
2 tsp. soy sauce
6 to 8 slices French bread (1/2 inch thick)
6 to 8 thin slices Swiss cheese, (about 4 oz.)

In a large skillet, melt butter over medium heat. Saute onions and mushrooms until tender. Place in a 12 x 7 1/2 x 2 inch baking dish or 2 quart casserole. Sprinkle shredded cheese on top. Combine soup, milk and soy sauce; pour over cheese, top with the bread, then the cheese slices. Cover and refrigerate 4 hours or overnight. Bake, loosely covered, at 375 degrees for 30 minutes. Uncover and bake 15 to 20 minutes longer or until nicely browned. Let stand 5 minutes before serving. Yield 6 to 8 servings.