1/2 c. onions, chopped
1/2 c. green pepper, chopped
1/2 c. celery, chopped
1 lb. mushrooms, sliced
1/2 c. butter
1/2 c. mayonnaise
8 slices white bread
3 eggs
1/2 c. milk

TOPPING:

1 can cream of mushroom soup
1 (4 oz.) can mushrooms, drained
1/4 c. mayonnaise
1/2 c. cream
1 c. Cheddar cheese, grated
Paprika

Saute vegetables in butter until tender. Add mayonnaise. Arrange 4 slices bread in well-buttered 9 x 13 inch baking pan, cutting bread to cover bottom of pan. Cover bread with vegetables. Arrange remaining slices of bread over vegetables. Beat eggs and milk and pour over bread. Refrigerate several hours (or up to 2 days). Mix first 4 topping ingredients and pour over casserole. Sprinkle cheese over top; then sprinkle paprika. Bake at 350 degrees for 45 minutes. Serves 12.