Preheat the oven to 350°F (175°C) and lightly coat a 9x13-inch baking pan with nonstick spray or a thin layer of oil.
Place a large skillet over medium heat. Add the ground beef and diced onion, cooking until the meat is fully browned and the onion is tender. Drain any excess grease.
Incorporate the minced garlic into the skillet and sauté for about 30 seconds, just until aromatic.
In a mixing bowl, whisk together the condensed soup, your choice of milk or broth, paprika, and a pinch of salt and pepper.
Transfer the cooked rice, beef mixture, half of the shredded cheddar, and the prepared sauce into the greased baking dish. Stir until thoroughly combined and evenly distributed.
Scatter the remaining cheddar cheese over the surface of the casserole. Cover the dish with aluminum foil and bake for 20 minutes.
Remove the foil and return the dish to the oven for another 10 minutes, or until the cheese has melted and developed a golden-brown finish.
Optionally, place under the broiler for 2 additional minutes for a crispier top layer.
Sprinkle with chopped parsley if desired and serve immediately while hot.