In a large bowl, combine the mashed potatoes with cooked bacon, cheddar, Parmesan, chives, garlic powder, salt and pepper. Stir together until all the ingredients are well combined.
In a shallow bowl, break in the eggs and beat them well. In another bowl, add the panko bread crumbs.
Using a small cookie scoop, scoop around 1 to 2 inches of the mashed potato mixture, and roll it into the ball shape in your hands.
Dredge the mashed potato ball in the beaten eggs covering all sides, then toss in the panko bread crumbs, making sure it coats all the sides. Repeat until all the mashed potato balls are dredged and coated.
Set a Dutch oven over medium heat, and pour in your vegetable oil until it reaches about 3 inches of depth. Allow it to heat until it reads 375°F (190°C) using a candy thermometer.
Once the oil is heated to our desired temperature, toss in the mashed potato balls and fry for about 3 minutes, until it is golden on all sides. Fry in batches as it can't all go at once.
Once fried, set the fried mashed potato balls on a plate lined with a paper towel so excess oil can drain.
Set on a plate and garnish with some extra salt, grated Parmesan, and chopped chives.