In a medium bowl, combine mashed potatoes, crumbled turkey bacon, salt, black pepper, and garlic powder if using. Mix well.
With lightly floured hands, scoop about 2 tablespoons of the mixture and flatten into a disk. Place a cube of cheddar cheese in the center and gently roll into a sealed ball.
Prepare three shallow bowls: one with flour, one with eggs whisked with milk, and one with breadcrumbs mixed with Parmesan.
Dip each ball into flour, then egg, then breadcrumbs. Repeat the egg and breadcrumb coating for extra crispiness.
Arrange the Air Fryer Cheesy Mashed Potato Balls in a single layer in the air fryer basket and lightly spray with oil.
Air fry at 370°F (188°C) for 4 minutes. Shake the basket, spray lightly with oil, and cook for another 2–3 minutes until golden brown.
Serve warm with your favorite dipping sauce.