01 - Preheat oven to 375°F. Lightly coat a 9x13-inch casserole dish with nonstick cooking spray.
02 - In a large nonstick skillet, sauté the chicken over medium heat for 4–5 minutes, until lightly browned but not fully cooked. Remove and set aside.
03 - In the same skillet, add onion, garlic, carrots, and bell pepper; sauté for 4 minutes until slightly softened.
04 - Add zucchini and cook for another 2 minutes.
05 - In a large bowl, combine sautéed vegetables, browned chicken, cooked brown rice, diced tomatoes, chicken broth, tomato paste, basil, oregano, smoked paprika, black pepper, and salt. Mix well.
06 - Transfer mixture to the prepared casserole dish, spreading evenly.
07 - Cover with foil and bake for 25 minutes.
08 - Remove foil, sprinkle mozzarella evenly over the top, and bake uncovered for 10–12 minutes until cheese is melted and bubbly.
09 - Let rest for 5 minutes before serving.