If you are using freshly made mashed potatoes, let them cool for 10 to 15 minutes so they are easier to handle. Leftover mashed potatoes can be used straight from the fridge; let them sit a few minutes at room temperature to soften slightly.

In a large bowl, add the mashed potatoes, egg, 1/2 cup flour, grated cheddar (if using), chopped chives or scallions, salt, pepper, and garlic powder. Stir until everything is combined into a soft, manageable mixture.

If the mixture feels too wet or sticky, add another tablespoon or two of flour until it holds its shape when scooped. Conversely, if it feels too dry, add a splash of milk or a small extra spoonful of mashed potato.

Shape the mixture into patties about 2 to 3 inches wide and 1/2 inch thick. For neat edges, dust your hands with a little flour. If you want an extra crispy exterior, press each patty into breadcrumbs on both sides.

Heat a large nonstick or cast-iron skillet over medium heat and add the oil. When the oil shimmers but is not smoking, add the patties in a single layer. Do not overcrowd the pan; fry in batches if needed.

Cook the fritters for 3 to 4 minutes per side, until golden brown and crisp. Flip gently with a spatula. Adjust heat if they brown too quickly; you want a golden crust and a warm, soft center.

Transfer cooked fritters to a paper towel-lined plate to drain excess oil. Serve hot with a dollop of sour cream, a squeeze of lemon, or your favorite dipping sauce.