Add 1 cup of water, 1/2 teaspoon of salt, and 1 teaspoon of olive oil to a saucepan and bring to a boil. Once it comes to a boil, add 1/2 cup of rice, cover, reduce the heat to medium-low and cook for 15 minutes.
While the rice cooks, brown the beef in a large skillet. Add the onions and cook for 2-3 minutes. Stir in the garlic, cayenne pepper, garlic powder, Italian seasoning, salt, and pepper, and cook for 1-2 minutes.
Add the cooked rice and 1 cup of marinara sauce to the ground beef and mix until well combined. Check for seasoning.
Cut the peppers in half lengthwise and discard the seeds and membranes. Brush the peppers with olive oil and season with salt and pepper.
Place the peppers in the air fryer basket and cook for 3 minutes at 400 degrees F.
Fill each pepper with the beef and rice mixture and top with the remaining sauce. Cook for 10 minutes at 350 degrees F.
Once the 10 minutes are up, top with cheese and cook for an additional 2 minutes.
Serve immediately and enjoy!