Preheat Air fryer if needed to the pre-set chicken option or 380 degrees.
Make horizontal cuts across each chicken breast.
Rub your chicken breasts with olive oil and fajita seasoning and then set to the side.
Place slices of bell peppers and red onions inside each cut.
Place the chicken in the air fryer vegetables side facing up.
Cook chicken for 15 min.
Remove from the air fryer and place on a parchment sheet covered baking pan.
Top each piece of chicken with a handful of cheese.
Set your oven to broil on high. Broil chicken until the cheese is melted.
Remove from oven and serve with some cilantro, salsa and sour cream.