Step 1: Prepare the Rice

1. Begin by preheating your oven to 350°F (175°C).
2. Rinse the rice under cold water until the water runs clear. This removes excess starch and prevents the rice from becoming sticky.
3. In a medium saucepan, combine the rinsed rice and beef broth. Bring it to a boil, then reduce the heat, cover, and simmer for about 15 minutes until the rice is tender and has absorbed the liquid. Remove from heat and set aside.

Step 2: Cook the Ground Beef

1. While the rice is cooking, heat a large skillet over medium heat. Add the olive oil and let it warm up.
2. Add the chopped onion and minced garlic to the skillet. Sauté for about 3-4 minutes, or until the onion becomes translucent and fragrant.
3. Add the ground beef to the skillet. Break it apart with a spatula and cook until it’s browned all the way through, about 8-10 minutes. Drain off any excess grease.
4. Season the beef with salt, pepper, paprika, and red pepper flakes (if using). Stir well to combine, then remove from heat.

Step 3: Assemble the Casserole

1. In a large mixing bowl, combine the cooked rice, ground beef mixture, cream of mushroom soup, cream of chicken soup, and milk. Stir until all the ingredients are well incorporated and smooth.
2. Transfer the mixture to a greased 9×13 inch baking dish, spreading it out evenly.

Step 4: Add the Cheese

1. Sprinkle the shredded cheddar cheese evenly over the top of the casserole.
2. Cover the baking dish with aluminum foil.

Step 5: Bake the Casserole

1. Place the covered casserole in the preheated oven and bake for 20 minutes.
2. After 20 minutes, remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden brown on top.
3. Once done, remove the casserole from the oven and let it cool for 5 minutes before serving.