Preheat the oven to 375°F (190°C) and lightly grease a 9x13 inch baking dish.
In a large skillet, heat olive oil over medium-high heat.
Add the ground turkey and diced onion to the skillet and cook until the turkey is browned and the onion is translucent, breaking the meat into small crumbles.
Stir in the minced garlic, oregano, basil, salt, and pepper, and cook for an additional 60 seconds.
Add the marinara sauce to the turkey mixture, reduce heat to low, and simmer for 5 minutes.
Layer half of the zucchini slices in the bottom of the prepared baking dish.
Spread half of the turkey and sauce mixture evenly over the zucchini layer.
Repeat with the remaining zucchini slices followed by the remaining turkey mixture.
Sprinkle the mozzarella and parmesan cheeses evenly over the top.
Bake for 25 to 30 minutes until the zucchini is tender and the cheese is melted and golden brown.
Remove from the oven and let rest for 5 minutes before serving.