Cut the tops off the bell peppers and remove the seeds to create shells for stuffing.

In a skillet over medium heat, brown the ground meat with the chopped onion and minced garlic until the meat is cooked and onions are translucent.

Stir in the cooked rice, diced tomatoes, Italian seasoning, salt, and pepper until well combined.

Generously fill each pepper with the meat mixture.

Arrange the stuffed peppers upright in the slow cooker.

Cover and cook on low for 6 to 8 hours, or on high for 3 to 4 hours.

If using cheese, sprinkle it on the stuffed peppers during the last 30 minutes of cooking to let it melt.

Serve warm and enjoy!