In a large bowl, mix the mashed potatoes (3 cups), eggs (2), onion powder (1 tsp), garlic powder (1 tsp), pepper (1/2 tsp), and salt (1/2 tsp) together in a bowl.
Stir in the breadcrumbs (1 cup) or flour (1/2 cup), cheese (1 cup), spring onions (2), and frozen peas (1 cup).
Form the mixture into 3-inch patties by rolling them into a ball and flattening them until they're about a 1/2 inch thick. Dredge each patty in extra flour.
Heat oil (3 tbsp) in a nonstick pan until hot and fry each patty for about 4 minutes per side, or until golden brown and crispy.Do not overcrowd the pan and do not flip the pancakes too soon or they won't develop a crisp crust. Transfer the pancakes to a paper towel-lined plate and immediately sprinkle them with salt.