Split the bagel in half and cut it into 1-inch cubes.
Add the cubes to a bowl and drizzle with olive oil. Toss to coat.
Add the garlic powder and grated Parmesan cheese and toss to coat.
Transfer to an air fryer tray, sprinkling any loose Parmesan on top.
Air fry for 6-8, shaking twice, until deep gold brown.
Let cool to room temperature before using or storing. They get crispier as they cool.
Video
Notes
Store leftover croutons in an airtight container at room temperature for 3-4 days.Freeze croutons for long-term storage. Let thaw on the counter before using.