Cut the tops off each bell pepper and carefully remove the seeds and white membrane from the interior, creating a hollow cavity for stuffing. Stand the peppers upright on a clean surface and set aside. This prep work can be done ahead of time, and I like to give the peppers a light rinse inside to remove any remaining seed debris.

Heat the olive oil in a large skillet over medium heat. Dice the onion finely and add it to the hot oil, stirring occasionally until softened and translucent, about 3-4 minutes. Increase heat to medium-high and add the ground beef, breaking it apart with a spoon as it cooks until completely browned and no pink remains, about 5-7 minutes. Drain any excess fat if needed before proceeding.

Add the diced tomatoes, tomato sauce, cooked rice, Italian seasoning, garlic powder, red pepper flakes, and a generous pinch of salt and black pepper to the cooked meat mixture. Stir everything together thoroughly to combine flavors evenly. Let the mixture simmer for 2-3 minutes to allow the spices to fully integrate. I find that freshly shredded cheese melts more evenly than pre-shredded varieties, so plan to shred yours right before the final step.

Spoon the filling mixture generously into each prepared bell pepper, packing it in firmly but not so hard that the pepper splits. Divide the filling evenly among the four peppers. Place the stuffed peppers upright in your air fryer basket (work in batches if needed, depending on your air fryer size), then air fry at 360°F for 10 minutes. This initial cook softens the peppers while the filling heats through.

Carefully remove the air fryer basket and top each pepper with an even portion of freshly shredded Colby Jack cheese. Return the basket to the air fryer and cook at 360°F for an additional 2-3 minutes, just until the cheese is melted and lightly golden. Don't skip the fresh shredding step—it truly does melt better than pre-shredded cheese, which has anti-caking agents that prevent smooth melting.