Preheat the Oven
Set your oven to 350°F (175°C). This moderate temperature will allow the casserole to heat thoroughly without burning the cheese topping, creating that perfect golden crust while keeping the inside moist and flavorful.
Brown the Meat
In a large skillet over medium heat, cook the ground beef until it's completely browned and no pink remains. Break up any large chunks with a wooden spoon as it cooks for even browning. Once fully cooked, drain off any excess fat to keep the dish from becoming greasy.
Add Aromatics
Add the chopped onion and minced garlic to the skillet with the beef. Sauté for 2-3 minutes until the onions become translucent and soft. This step builds the flavor foundation of your casserole, as the aromatics release their essential oils when cooked.
Combine Main Ingredients
Stir the uncooked rice, beef broth, undrained diced tomatoes, frozen vegetables, and Italian seasoning into the beef mixture. Season with salt and pepper according to your taste preferences. Bring everything to a boil, which will kickstart the cooking process for the rice.
Simmer the Mixture
Reduce the heat to low, cover the skillet, and allow the mixture to simmer for approximately 15 minutes. During this time, the rice will absorb the flavorful liquid and become tender. Most of the liquid should be absorbed, but the mixture should still be slightly moist.
Prepare for Baking
Transfer the entire mixture to a greased 9×13-inch baking dish, spreading it out evenly. Sprinkle the shredded cheddar cheese uniformly across the top of the casserole to create a delicious, melty layer.
Bake to Perfection
Place the baking dish in the preheated oven and bake for 20-25 minutes. The casserole is ready when the cheese has completely melted, turned golden, and is bubbling around the edges. Serve hot for the best taste experience.