In a large bowl, combine the mashed potatoes, 1 beaten egg, grated cheese, ham or bacon (if using), green onions or chives, salt, and pepper. Mix until well combined.
Roll spoonfuls of the mixture into uniform small logs or balls.
Set up three shallow dishes: one with flour, one with the 2 beaten eggs, and one with breadcrumbs.
Roll each croquette in flour and shake off the excess, dip in the egg, then coat in breadcrumbs.
Preheat the air fryer to 400°F (200°C) for 5 minutes.
Arrange the croquettes in a single layer in the basket, leaving space between them, and mist lightly with cooking spray.
Air fry at 400°F for 10 to 12 minutes, flipping halfway through, until golden brown and crisp. Work in batches if needed.
Rest on a wire rack for a couple of minutes, then serve warm with your favorite dipping sauce.