3 sauteed mushroom butter sandwiches Recipes

unsalted butter, cremini mushrooms, trimmed and chopped, salt, black pepper, dry white wine, chilled italian fontina , rind discarded and cheese coarsely grated (2 cups), chopped fresh flat-leaf parsley, very thin slices firm white sandwich bread, white-truffle oil (optional)

submarine rolls, halved, soft butter (can use more butter if desired), garlic powder (optional), sliced mushrooms, well drained (can use fresh sauteed sliced mushrooms), onion, thinly sliced, green bell pepper, seeded and sliced into strips, seasoning salt (to taste) or white salt & freshly ground black pepper (to taste), sliced cooked beef, mozzarella cheese or 8 provolone cheese