Preheat your oven to 375°F (190°C). Lightly grease a 9x13-inch baking dish with olive oil.

In a large skillet over medium heat, heat olive oil. Add chopped onion and minced garlic, sautéing for about 2 minutes until fragrant.

Introduce ground turkey to the skillet, breaking it up. Cook for approximately 5-6 minutes until browned and fully cooked.

Stir in the drained diced tomatoes, dried Italian herbs, salt, and black pepper. Let it simmer for 3-4 minutes.

Layer half of the sliced zucchini at the bottom of the greased baking dish, followed by half of the turkey mixture, and half of the shredded mozzarella cheese. Repeat layers.

Place the casserole in the oven and bake uncovered for 30-35 minutes until bubbling and cheese is golden brown.

Remove from the oven and let it cool for about 5 minutes before serving.