Place toast on baking sheet. Spread with butter if desired. Cover with mushrooms and tomato slices. Sprinkle cheese and crumbled bacon on top. Bake in 350 degree oven until cheese melts. 1 serving 147 cal or 1 bread, -20ºC at and 1 lean meat exchange (without butter) or 182 cal or 1 bread, -20ºC at and 1 lean meat exchange (with butter).