Preheat the oven to 375°F (190°C) and lightly grease a 9×13-inch casserole dish.

Cook the chicken: In a large skillet, heat the olive oil over medium heat. Add the diced chicken, season with salt and pepper, and cook until no longer pink. Remove from the skillet and set aside.

Sauté the vegetables: In the same skillet, add a little more oil if needed, then sauté the diced onion for 2–3 minutes until softened. Add the minced garlic and sliced mushrooms, cooking until the mushrooms release their moisture and become golden.

Mix the base: In a large mixing bowl, combine the uncooked rice, cooked chicken, sautéed vegetables, chicken broth, milk, cream of mushroom soup, paprika, salt, and pepper. Stir well to combine all the ingredients evenly.

Transfer to baking dish: Pour the mixture into the prepared baking dish and spread evenly. Cover tightly with aluminum foil to keep the moisture locked in during baking.

Bake the casserole: Bake for 50–55 minutes, or until the rice is tender and has absorbed most of the liquid. At this point, remove the foil.

Add the cheese: Sprinkle the shredded cheese over the top of the casserole. Return to the oven, uncovered, and bake for an additional 10 minutes until the cheese is melted and bubbly.

Let it rest: Once baked, allow the casserole to rest for 5–10 minutes before serving. This helps the flavors settle and makes it easier to scoop.