Place cold mashed potatoes into a large mixing bowl. Add green onion, chopped bacon, garlic powder, black pepper, and 1 egg - mix well.
With lightly floured hands - pick up a tablespoon sized ball of potato mixture and flatten into a small pancake. Place a cube of cheddar in the center and wrap the potato mixture around the cheese. Repeat.
In three separate bowls, add flour, remaining egg (whisked) and breadcrumbs. Coat the potato ball in flour, then egg, then breadcrumbs. Coat once more with egg and once more with bread crumbs. Set aside - store in fridge while you wait to fry.
In a medium pan heat oil over medium/high heat (to approximately 350˚F (180˚C). Fry the potatoes in batches until browned on all sides.
Transfer fried potato balls to paper towels to drain excess oil. Sprinkle with salt.
Transfer to a baking tray and bake in a preheated oven for 5 minutes at 400˚F (200˚C).