Butterfly the chicken breasts and open them up. Smear 1 tbsp pesto over each one and then place 2 mozzarella slices in each.
Close the chicken back up again (you can use a skewer or cocktail stick to keep it in place) and place in the air fryer basket.
Cut the baby potatoes in half and add to a bowl with the olive oil, garlic granules, Italian seasoning and a generous helping of salt. Toss to coat then empty into the air fryer basket in an even layer around the chicken.
Cook at 185C for 20 minutes and serve. If using the oven, cook on a baking tray at 200C for 25-30 minutes until the chicken is cooked through.