Preheat oven to 350°F (175°C).
In a skillet, heat olive oil and sauté onion and garlic until fragrant.
Stir in spinach and cook until just wilted.
In a large bowl, mix cooked chicken, rice, sautéed vegetables, cream of chicken soup, sour cream, salt, pepper, and paprika.
Transfer mixture to a greased 9x13 baking dish.
Sprinkle mozzarella and cheddar evenly on top.
Bake uncovered for 25–30 minutes, until bubbly and golden on top.
Let it cool slightly before serving.