Butter an oven dish generously.
Arrange a layer of buttered slices of white or brown bread on the base of the dish.
On this place a layer of sliced tomatoes, skinned and seasoned, then a layer of washed and peeled mushrooms, gill side up and well seasoned.
Repeat these layers once again, and dot top mushroom layer with butter.
Cover and bake in hot oven for 15 minutes, then remove lid and bake for another 10 minutes, or until the mushrooms are done.