Wash and dry the tomatoes. Cut off a thin slice from the stem end of each tomato and scoop out the pulp. Season the tomato shells lightly with salt and pepper and reserve; reserve half of the pulp.
Wipe the mushrooms and reserve eight of the caps. Chop the remaining mushrooms. Melt twotablespoons of the butter and in it sauté the mushroom caps briefly. Remove mushrooms from the pan and set aside. Add the onion and chopped mushrooms to the butter left in the pan and cook for three minutes. Add the bread crumbs, reserved tomato pulp, parsley, one teaspoon salt and one-eighth teaspoon pepper. Cook for three minutes longer.
Cut the chicken livers into bite-size pieces and sauté them in the remaining butter. Add them to the bread-crumb mixture along with the wine; blend well. Fill the tomato shells generously with the mixture. Dot with additional butter and top with the mushroom caps.
Place in a well-buttered baking pan and bake for twenty minutes.