Place the mashed potatoes, parsley and cheese in a large bowl and mix together.

Place a rimmed baking sheet or large plate on the table.

Scoop up some of the mashed potatoes mixture (roughly 3 to 4 tablespoons) and roll a 1-inch by 2 ½-inch oval football shape.

Beat the egg and salt together in a medium bowl.

Place the flour in another bowl and the panko bread crumbs in a third bowl.

Roll one of the balls in the flour to coat.

Then dunk and roll in the beaten egg. Let any excess egg drip off.

Then roll the croquette in the bread crumbs until coated.

Place on the baking sheet/plate and repeat with the remaining mashed potato mixture.

Once all the mashed potatoes are coated, pour enough frying oil in a medium sized skillet for it to be ½-inch deep.

Heat the oil until it reaches 350°F or until a pinch of panko crumbs sizzles and immediately turns brown when dropped in.

Carefully place a batch of croquettes in the hot oil, making sure not to crowd the pan too much.

Fry for 45 to 60 seconds on one side, until it starts to get golden brown, then turn the croquette ⅓ the way over, and fry for an additional 45 to 60 seconds, repeating a third time until the entire croquette is golden brown.

Move the fried croquettes to a wire rack placed over a rimmed baking sheet or a plate lined with paper towels.

Repeat with the remaining croquettes, waiting for the oil to reheat to the hot temperature between batches.

Sprinkle salt, pepper and parsley to garnish and serve while hot.