Place an oven rack in the center position. Preheat the oven to 375°F.
Coat the bottom and sides of a 9 × 13-inch baking dish with nonstick cooking spray.
Place the uncooked rice in a fine-mesh sieve. Rinse it under cool running water for 30 to 60 seconds, moving the grains gently with your fingers. Let the excess water drain away.
Heat a large skillet over medium-high heat. Add the ground beef and cook for 6 to 8 minutes, breaking it into small crumbles as it browns. Continue cooking until no pink meat remains.
Remove the skillet from the heat. Carefully spoon the excess grease into a heat-safe container. Leave about 1 teaspoon of grease in the skillet to cook the onion.Do not pour hot grease down the sink. Return the skillet to medium heat. Add the diced onion and cook for 4 to 5 minutes, stirring often. The onion should look soft and slightly clear around the edges.
Add the minced garlic. Cook for 30 seconds, stirring constantly, until fragrant. Do not let the garlic turn dark brown.
Stir in the tomato sauce, undrained diced tomatoes, Italian seasoning, paprika, salt, and black pepper. Cook for about 1 minute, scraping any browned pieces from the bottom of the skillet.
Spread the rinsed rice evenly across the prepared baking dish. Spoon the beef and tomato mixture over the rice. Pour in the beef broth.Stir slowly until the rice is spread evenly through the mixture. Press any rice grains stuck to the sides of the dish back under the liquid. Cover the baking dish tightly with aluminum foil. Press the foil firmly around all four edges so steam cannot escape.
Bake the covered casserole at 375°F for 50 to 55 minutes.Check a spoonful of rice from the center after 50 minutes. The grains should be tender, and most of the liquid should be absorbed.If the rice is still firm, add ¼ cup hot beef broth, cover the dish again, and bake for another 5 to 10 minutes. Carefully remove the foil, keeping your hands and face away from the hot steam. Sprinkle the shredded cheddar evenly over the casserole.
Return the uncovered dish to the oven. Bake for 5 to 7 minutes, until the cheese is fully melted and bubbles appear around the edges.For a lightly browned top, broil the casserole for 1 to 2 minutes. Watch it closely because cheese can burn quickly. Remove the casserole from the oven. Let it rest for 5 to 10 minutes before serving. This gives the rice time to absorb any remaining liquid and helps each portion hold together.Top with chopped parsley, if desired.