Preheat the oven to 350°F (175°C). Lightly grease a 9×13-inch baking dish.
In a large skillet over medium heat, cook the ground beef and diced onion until the beef is browned and the onion is tender, about 6–8 minutes. Drain any excess grease.
Add the minced garlic and cook for 30 seconds until fragrant.
In a medium bowl, whisk together the cream of mushroom soup, milk (or beef broth), paprika, salt, and black pepper until smooth.
Add the cooked rice, beef mixture, soup mixture, and 1 cup of the shredded cheddar cheese to the prepared baking dish. Stir until everything is evenly combined.
Sprinkle the remaining 1 cup of cheddar cheese evenly over the top.
Cover the dish with aluminum foil and bake for 20 minutes.
Remove the foil and continue baking for 10 minutes, or until the cheese is melted, bubbly, and lightly golden.
For an extra crispy cheese topping, broil for 2 minutes, watching carefully to prevent burning.
Garnish with chopped parsley if desired and serve hot.