Preheat oven to 375°F (190°C). Spray a 9x13 baking dish with cooking spray.

Cook the turkey:

In a large skillet, cook ground turkey over medium heat until browned. Drain excess liquid if needed.

Add vegetables:

Add onion, bell pepper, and zucchini. Cook until softened (5–7 minutes).

Mix in beans and corn:

Stir in black beans, corn, diced tomatoes (with juices), taco seasoning, and water. Simmer for 5 minutes.

Assemble the casserole:

Pour the mixture into the prepared baking dish. Sprinkle cheese evenly on top.

Bake:

Bake uncovered for 15–20 minutes, or until cheese is melted and bubbly.

Serve:

Let it rest 5 minutes before serving. Garnish with chopped cilantro, salsa, or fat-free Greek yogurt (optional).