Preheat your oven to 350°F (175°C). Lightly grease a 9x13-inch casserole dish with butter or non-stick cooking spray to prevent sticking.

Rinse the rice under cold water in a fine-mesh strainer until the water runs clear, about 30 seconds. Drain thoroughly to prevent it from becoming gummy.

In a large mixing bowl, whisk together the cream of mushroom soup, milk, water, and onion soup mix until smooth and evenly combined with no lumps.

Spread the rinsed rice evenly across the bottom of the greased casserole dish in a single layer. Pour the soup mixture over the rice, ensuring every grain is coated. Gently shake the dish and tap it on the counter to allow the liquid to settle evenly and release air bubbles.

If chicken breasts are uneven in thickness, gently pound the thicker parts for uniform cooking. Place the chicken breasts on top of the rice mixture, pressing them down slightly so they are about halfway submerged. Sprinkle paprika, salt, and black pepper evenly over the chicken.

Cover the casserole dish tightly with aluminum foil, tenting it slightly so it doesn’t touch the chicken. Bake in the preheated oven for 45 minutes without opening.

After 45 minutes, carefully remove the foil (watch for hot steam). Check that the rice is tender and the chicken has reached an internal temperature of 165°F using an instant-read thermometer inserted into the thickest part. Most liquid should be absorbed.

Sprinkle the shredded cheddar cheese evenly over the top. Return the uncovered dish to the oven and bake for another 15 minutes, or until the cheese is melted, bubbly, and lightly golden around the edges.

Remove from the oven and let rest for 5-10 minutes to allow the sauce to thicken. Garnish with fresh parsley and serve hot.