Step 1: Prepare the Mixture
1. Combine Ingredients: In a large mixing bowl, combine the leftover mashed potatoes, shredded cheese, grated Parmesan cheese, egg, flour, garlic powder, onion powder, salt, and pepper. Mix until well combined. The mixture should hold together; if it’s too wet, add a bit more flour.

Step 2: Shape the Puffs
1. Form Puffs: Using your hands or a spoon, scoop out a portion of the mixture and shape it into small balls or patties (about 1-2 inches in diameter). Dust your hands with flour if the mixture is sticky.

Step 3: Fry the Puffs
1. Heat Oil: In a large skillet, heat about 1/2 inch of oil over medium heat until hot (around 350°F or 175°C).
2. Fry Puffs: Carefully add the potato puffs to the hot oil, a few at a time, being careful not to overcrowd the pan. Fry for about 3-4 minutes on each side, or until golden brown and crispy.
3. Drain: Use a slotted spoon to remove the puffs from the oil and place them on a paper towel-lined plate to drain excess oil.

Step 4: Serve
1. Enjoy: Serve the cheese puffs warm with your favorite dipping sauce, such as ranch, ketchup, or sour cream.