Preheat oven to 400 degrees.

Bring a pot of water to a boil.

Cut the zucchini in half lengthwise. Using a small spoon, scoop out the flesh and set it aside. Put the zucchini in the boiling water and boil for about 2 minutes.

Brown the turkey sausage. Once browned, remove the sausage and set it aside.

Add a drizzle of olive oil to the pan. Add the chopped onions and garlic and cook until translucent. Chop the reserved zucchini and add it to the onion and garlic. Add the browned sausage back to the pan and mix well.

Cover the bottom of a baking dish with a thin layer of tomato sauce. Place the zucchini cut side up in the dish. Fill each zucchini with the sausage mixture. Add a couple of spoonfuls of tomato sauce to the top of each zucchini. Add a tbsp of shredded mozzarella cheese and a sprinkle of grated Parmesan cheese to the top of each.

Cover with foil and bake for 35 minutes.