Preheat your oven to 350°F. Lightly coat a 9x13-inch baking dish with nonstick spray or a thin layer of butter.

In a large skillet over medium-high heat, cook the ground beef and diced onion, breaking the meat into crumbles, until the beef is browned and the onion is translucent, about 6 to 8 minutes. Drain off any excess fat.

Add the minced garlic to the skillet and sauté for 30 seconds, until fragrant, stirring constantly.

In a medium bowl, whisk together the cream of mushroom soup, milk or broth, smoked paprika, and a generous pinch of salt and pepper until smooth.

In the prepared baking dish, combine the cooked rice, the beef-onion mixture, half of the shredded cheddar, and the soup mixture. Stir everything together until evenly distributed.

Sprinkle the remaining cheddar cheese evenly over the top. Cover the dish with aluminum foil and bake for 20 minutes.

Remove the foil and continue baking for another 10 minutes, until the cheese is melted and bubbly and the casserole is heated through.

For a golden, crispy cheese crust, switch the oven to broil and cook for 1 to 2 minutes, watching closely so it doesn't burn.

Let the casserole rest for 5 minutes, then garnish with chopped parsley if desired. Serve hot.