Preheat your oven to 375°F (190°C) and coat a 9x13-inch baking dish with non-stick cooking spray.

In a large skillet over medium heat, add olive oil and sauté the diced onion and minced garlic for about 3-4 minutes.

Add the ground turkey to the skillet, cooking until browned, about 5-7 minutes, and season with Italian seasoning, salt, and pepper.

Stir in the sliced zucchini and drained diced tomatoes, cooking for an additional 5 minutes.

Remove from heat and mix in half of the shredded cheese until melted.

Pour the mixture into the prepared baking dish, smoothing it out evenly.

Top with the remaining shredded cheese and grated Parmesan cheese, then add breadcrumbs if desired.

Bake for 20-25 minutes until the cheese is bubbly and the top is golden brown.

Let cool for a few minutes before serving.