Preheat over to 400°.
Cut loaf of bread in half. Hollow out the center,leaving the thick crust as a shell Reserve 1 1/2 cups of the bread crumbs.
In a skillet,combine beef, onions, oregano, salt and pepper and brown.
Mix browned meat in a large bowl with crumbs, mustard, parsley, egg and cheese. Blend thoroughly.
Fill bread loaf with mixture and secure with toothpicks.
Brush with melted butter and wrap in aluminum foil and bake for 10 minutes.
Loosen foil and bake another 10 minutes.
Slice and serve.