Trim the ends of the zucchini, then cut in half lengthwise. Use a spoon or a melon baller to scoop out the seeds and discard. Make sure to remove enough zucchini pulp to make a good-sized hollow.

Oil the baking dish with vegetable oil then place the zucchini halves into a 9x13 baking dish and set aside.

Add the ground beef, salt, and pepper to your skillet and brown over medium-high heat.

Reduce heat to medium and add the garlic, onions, and peppers. Cook until the onions are tender and the ground beef is done.

Pour in the tomato sauce, parmesan cheese, and 1/2 cup of mozzarella cheese. Stir until the cheese has melted into the meat sauce.

Spoon the meat sauce into the hollowed zucchini.

Cover with aluminum foil and bake for 45 minutes.

Remove the zucchini from the oven and uncover. Sprinkle the remaining mozzarella cheese over top using about 1/4 cup on each zucchini half. Return to the oven and bake for another 5 minutes or until the cheese has melted and is bubbling.