Preheat your oven to 350°F (175°C).
In a large skillet, brown the ground beef over medium heat.
Add the chopped onion and bell pepper to the skillet, cooking until softened.
Stir in the canned tomatoes, rice, beef broth, garlic powder, salt, and pepper.
Bring the mixture to a simmer, then remove from heat.
Transfer the mixture to a greased 9x13 inch casserole dish.
Sprinkle shredded cheese evenly over the top.
Cover the dish with aluminum foil and bake for 30 minutes.
Remove the foil and bake for an additional 10-15 minutes, or until the cheese is bubbly and golden.
Let the casserole rest for 10 minutes before serving.