Add the leftover mashed potatoes to a large bowl. They shouldn't be cold from the fridge if you can help it - let them stand at room temperature for 30 minutes before adding any other ingredients OR mash them up well again to break up the clumps with a warm potato masher.
Add the cheese, flour, green onion, bacon or ham, eggs, garlic powder, thyme, and salt and pepper.
Stir all the ingredients together very well until everything is fully incorporated and the mixture is smooth.
Form the mixture into 12 patties about 1.5 centimetres thick.
Heat a large non-stick skillet over medium heat and add a small amount of vegetable oil (around 1-2 teaspoons).
Fry the patties in batches (don't overcrowd your skillet!) for about 5 minutes per side or until golden brown and completely cooked through.
Enjoy warm with a dollop of sour cream, some more sliced green onions, and some extra cheese, if desired.
