Preheat your air fryer to 350°F (175°C) for 2–3 minutes.
Mix the softened butter, minced garlic, parsley, and a pinch of salt together in a small bowl until well combined.
Spread the garlic butter generously over the cut sides of the bread.
Top evenly with the shredded mozzarella and Parmesan cheese.
Place the bread cut-side up in the air fryer basket. You may need to work in batches depending on your air fryer size.
Air fry at 350°F for 6–8 minutes, until the cheese is melted, bubbly, and golden at the edges.
Remove carefully, sprinkle with red pepper flakes if using, slice, and serve immediately.