Heat the oven: Preheat to 375°F (190°C). Grease a 9x13-inch baking dish with a little oil or butter.
Mix the base: In the dish, combine rice, chicken broth, condensed soup, milk, onion, garlic, thyme, and paprika.
Season with 1 teaspoon salt and 1/2 teaspoon pepper. Stir well.
Add vegetables and chicken: Fold in the frozen veggies. Add the chicken pieces, toss to coat, and spread everything into an even layer.
Drizzle fat: Spoon the olive oil or melted butter over the top.
This helps the rice cook evenly and adds flavor.
Cover and bake: Tightly cover with foil and bake for 35 minutes.
Uncover and finish: Remove the foil, stir gently, and check liquid levels. Bake uncovered for another 15–20 minutes, until the rice is tender and the chicken is cooked through.
Add cheese (optional): Sprinkle cheese over the top and bake 5 more minutes, until melted and bubbly.
Rest and serve: Let the casserole sit for 5–10 minutes. Taste and adjust salt and pepper.
Garnish with parsley if you like.