Transform leftover mashed potatoes into crispy and flavorful mashed potato balls using a food processor and an air fryer. In the food processor, combine the mashed potatoes, shredded cheese, chopped green onions, and cooked bacon. Pulse until well combined. Shape the mixture into small balls and place them on a baking sheet. Freeze the balls for about 30 minutes to firm up. Preheat the air fryer to 375°F and place the frozen mashed potato balls in a single layer. Cook for about 10-12 minutes, or until the balls are golden brown and crispy. Serve hot as a tasty appetizer or side dish!