Heat olive oil in a large skillet over medium-high heat.
Add ground beef to the skillet and cook, breaking it apart with a spoon, until browned and no longer pink, about 5 minutes.
Drain excess fat from the skillet if necessary.
Add diced onion and minced garlic to the skillet with the beef and cook until the onion is softened, about 3 minutes.
Stir in diced green and red bell peppers and cook for 2 minutes until slightly tender.
Add uncooked rice to the skillet and stir to combine with the beef and vegetables.
Pour in beef broth and diced tomatoes with their juice.
Add dried Italian seasoning, salt, black pepper, and crushed red pepper flakes. Stir well to combine.
Bring the mixture to a boil, then reduce heat to low and cover the skillet with a lid.
Simmer for 18 to 20 minutes, or until the rice is cooked and liquid is absorbed.
Remove the skillet from heat and sprinkle shredded cheddar cheese evenly over the top.
Cover the skillet again and let it sit for 2 minutes to allow the cheese to melt.
Serve hot, scooping portions of the unstuffed peppers skillet onto plates.