Preheat oven to 375°F (190°C).
In a large oven-safe skillet over medium-high heat, brown 1 pound of lean ground beef, breaking it up with a spoon, until no longer pink; drain off excess grease.
Add 1 medium yellow onion (chopped) and cook for about 5 minutes, until the onion softens.
Stir in 2 cups of chopped bell peppers and cook for 3–5 minutes, until they begin to soften.
Add one 14.5-ounce can of diced tomatoes (undrained), one 15-ounce can of tomato sauce, 1 cup uncooked long-grain white rice, 1 cup beef broth, 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon Italian seasoning, 1 teaspoon salt, and 1/2 teaspoon black pepper; stir to combine.
Bring the mixture to a gentle simmer, then remove from heat.
If not using an oven-safe skillet, transfer the mixture to a 9×13-inch baking dish and cover tightly with aluminum foil.
Bake for 30 minutes, until the rice is tender and most of the liquid is absorbed.
Remove foil, sprinkle 1½ cups shredded cheddar cheese evenly over the top, and bake uncovered for 10–15 minutes, until the cheese is melted, bubbly, and edges are golden.
Let rest for 5–10 minutes before serving.