Get Ready to Bake: Preheat your oven to a cozy 400°F (200°C). Lightly mist a 9x13 inch casserole dish with cooking spray – this makes cleanup a breeze!
Craft Your Meatballs: In a roomy mixing bowl, combine the ground turkey, Italian sausage, 1 cup of shredded mozzarella, Parmesan cheese, that sneaky shredded zucchini, egg, dried minced onion, dried minced garlic, dried basil, salt, and pepper. Mix everything thoroughly with your hands or a spatula until it's well combined.
Form and First Bake: Using a large cookie scoop or your hands, shape the mixture into about 24 meatballs. Arrange them neatly in your prepared casserole dish. Bake for approximately 30 minutes, or until the meatballs are cooked through and start to turn a lovely golden brown.
Drain and Top: Carefully take the dish out of the oven. Gently pour off any excess cooking liquid to prevent your casserole from becoming watery. Now, pour your sugar-free marinara sauce evenly over the meatballs, followed by a generous sprinkle of the remaining 8 ounces of shredded cheese.
Final Melt and Golden Finish: Return the casserole to the oven for another 10-15 minutes, allowing the cheese to melt into a bubbly, golden layer. For an extra special golden-brown topping, you can briefly broil the casserole for 3-4 minutes – just keep a very close eye on it so it doesn't burn!
Serve with Joy: Let the casserole cool for a few minutes before serving. It's a perfect, easy-to-make healthy meal for any night!