Saute hamburger meat, Italian sausage, onion and garlic until cooked. Drain grease. Put meat mixture in large bowl.

Add breadcrumbs, oregano, salt, pepper and tomato sauce to meat mixture. Mix well.

In a skillet, par boil zucchini in water till tender. Remove zucchini and cut in half-length-wise. Remove seeds with a spoon, creating out a "tunnel" indentation in the zucchini (this will hold the filling-see photo below). Poke holes in zucchini with fork, then brush melted butter all over surface of the zucchini. Season with salt and pepper. Place zucchini halves in a 9x13 baking dish.

Stuff both the carved "tunnels" with the hamburger mixture. Sprinkle with Parmesan cheese.

Cover pan with aluminum foil. Bake at 350 degrees for 25-30 minutes. Remove from oven. Uncover.

Divide grated Mozzarella cheese in half. Sprinkle across top surface of both halves. Place pan back into the oven (uncovered) and continue baking for another 10-15 minutes, or until cheese has melted.

Remove from oven and cut into serving sizes (can usually get 2-3 servings per half, but it depends of course, on the size zucchini you are using). Serve, and enjoy!