In a large skillet, heat the olive oil over medium heat. Add the diced onion and sauté for about 3-4 minutes until translucent. This step enhances the flavor of the onion.

Add the minced garlic and sauté for an additional 1 minute until fragrant. Garlic can burn quickly, so keep an eye on it.

Add the ground beef to the skillet, breaking it up with a wooden spoon. Cook until browned, about 5-7 minutes. Ensure the beef is cooked through to avoid any food safety issues.

Stir in the diced tomatoes, Italian seasoning, salt, and black pepper. Cook for another 2-3 minutes to combine the flavors.

In a mixing bowl, combine the uncooked rice and beef broth. This will allow the rice to absorb the flavors from the broth as it cooks.

Preheat your oven to 350°F (175°C).

In a casserole dish, combine the beef mixture with the rice and broth mixture. Stir well to ensure even distribution.

Top the mixture with the shredded cheddar and mozzarella cheeses. Reserve some cheese for topping later if desired.

Cover the casserole dish with aluminum foil and bake in the preheated oven for 25 minutes. This helps the rice cook evenly and absorb the flavors.

After 25 minutes, remove the foil and bake for an additional 5-10 minutes, or until the cheese is bubbly and golden brown. This step adds a delicious crust to the cheese.

Remove the casserole from the oven and let it sit for about 5 minutes before serving. This allows the casserole to set and makes it easier to serve.

Serve warm, garnished with additional cheese or fresh herbs if desired.