1. Preheat your oven to 375 F (190 C). Lightly grease a 9×13 inch baking dish with cooking spray or a little olive oil.

2. Heat the olive oil in a large skillet or Dutch oven over medium-high heat. Add the chicken pieces and cook until lightly browned on all sides, about 5-7 minutes. Remove the chicken from the skillet and set aside. Add the chopped onion to the same skillet and cook until softened, about 3-4 minutes. Stir in the minced garlic and cook for another minute until fragrant.

3. In a large mixing bowl, whisk together the condensed cream of chicken soup, milk, chicken broth, Italian seasoning, salt, and black pepper until smooth. This forms the creamy base of your casserole.

4. To the bowl with the sauce, add the cooked rice, cooked chicken, broccoli florets, and 1.5 cups of the shredded cheddar cheese. Stir everything gently until all ingredients are well combined and coated in the sauce.

5. Pour the entire mixture into your prepared 9×13 inch baking dish, spreading it evenly. Sprinkle the remaining 1/2 cup of shredded cheddar cheese over the top of the casserole.

6. Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the casserole is bubbly around the edges and the cheese on top is melted and lightly golden brown. The chicken should be cooked through, and the broccoli tender-crisp.

7. Once out of the oven, let the casserole rest for 5-10 minutes before serving. This allows the sauce to set slightly, making it easier to serve.