Step 1: Preheat the Oven
Preheat your oven to 375°F (190°C) and lightly grease a 9×13-inch baking dish with olive oil or cooking spray to prevent sticking.

Step 2: Prepare the Ingredients
If your rice isn’t already cooked, prepare it according to the package instructions. You can use any variety of rice, but long-grain white rice, brown rice, or even basmati work well for this casserole.

Lightly steam the broccoli florets until they’re bright green and slightly tender, but not fully cooked (about 3-4 minutes in the microwave or on the stovetop). Set them aside.

Step 3: Combine Chicken, Rice, and Broccoli
In a large bowl, combine the cooked rice, shredded or cubed chicken, and steamed broccoli. Mix everything together gently, ensuring the ingredients are evenly distributed throughout.

Step 4: Add the Pesto and Cheese
Add ¾ cup of pesto sauce to the rice mixture, along with the sour cream or Greek yogurt for a creamier texture (if desired). Season the mixture with garlic powder, onion powder, salt, and pepper. Stir everything together until the pesto is fully incorporated and the ingredients are evenly coated.

Step 5: Assemble the Casserole
Transfer the chicken, rice, and broccoli mixture to the greased baking dish. Spread it out evenly in the dish, pressing it down lightly to ensure it bakes uniformly. Sprinkle 1 ½ cups of shredded mozzarella cheese evenly over the top, followed by a generous sprinkling of Parmesan cheese.

Step 6: Bake the Casserole
Place the casserole in the preheated oven and bake uncovered for 20-25 minutes, or until the cheese is melted and bubbly, and the casserole is heated through. For a golden, crispy cheese topping, broil the casserole for the last 2-3 minutes of baking, watching carefully to avoid burning.

Step 7: Garnish and Serve
Once baked, remove the casserole from the oven and let it rest for 5 minutes before serving. Garnish with fresh basil leaves for added flavor and a pop of color. Serve hot.