4 slices white sandwich bread
1 sm. onion, chopped
1/2 c. sliced fresh mushrooms
2 tbsp. butter, melted
1 c. chopped cooked ham
1 c. (4 oz.) shredded Swiss cheese
1 c. (4 oz.) shredded Cheddar cheese
1 tbsp. all purpose flour
1 1/4 c. milk
4 lg. eggs, beaten
1 tsp. prepared mustard
1/2 tsp. garlic salt

Place bread slices in bottom of a lightly greased 8 inch square baking dish; set aside. Saute onion and mushrooms in butter until tender; spoon evenly over bread. Top with ham. Combine cheeses and flour; sprinkle over ham. Combine milk and next 3 ingredients; pour over cheese. Cover and chill 8 hours. Remove from refrigerator, and let stand at room temperature 30 minutes. Bake at 375 degrees for 35 minutes or until set. Let stand 10 minutes before serving. Garnish with parsley sprigs if desired. 4 to 6 servings.