Place the potatoes in a pot and cover with water. Bring to a boil, reduce heat and simmer for 10-12 minutes or until potatoes are tender, but not falling apart. Drain potatoes and place on a rimmed sheet pan.
Use the flat bottom portion of a one cup measure, glass or other 3-4" wide flat surface to gently smash the potatoes to about ½" thick. Add the duck fat to the potatoes and gently toss the potatoes to coat them with the duck fat. Sprinkle with salt and pepper and roast for 15 minutes.
Using a spatula, flip the potatoes and return them to the hot oven for an additional 15-20 minutes. Remove from oven and sprinkle with parsley. Serve.