Cut off both ends of the onions; slice onions into 1/4-inch slices and separate the rings.
Place the flour and beaten eggs in separate bowls.
In a third bowl, combine the breadcrumbs, Parmesan and seasonings; mix well.
Dip the rings in the flour (shaking off excess) and then in the eggs until completely coated (allow excess egg to drip off); next, dip in the breadcrumb mixture to coat.
Place coated onion rings on a wire rack or a baking sheet lined with wax paper.
Spray the tops with cooking spray.
Spray air fryer basket with oil using an oil mister bottle.
Working in batches, transfer onion rings to the air fryer.
Cook at 375°F for 6 - 8 minutes.
Remove from the basket and continue with the next batch.