cook the bacon in a cast iron skillet and tear into pieces (save the bacon fat)

meanwhile, saute the onion until soft

mix the onion, bacon, and butter with the mashed potatoes (I skipped the butter because I had already put plenty in the mashed potatoes)

form into patties and dredge in flour

cook patties on medium heat (using the bacon fat) until they are brown and crispy on the edges, a few minutes each side.