In a large mixing bowl, combine cooled mashed potatoes, all-purpose flour, salt, and melted butter. Stir until a sticky dough forms, about 3–4 minutes.

Lightly flour your work surface and turn out the sticky dough. Knead for about 1–2 minutes until smooth, being careful not to over-knead.

Roll the dough into a flat circle about 1/4 inch thick, taking care not to tear it. Sprinkle flour if sticking occurs.

Slice the rolled dough into four equal wedges using a sharp knife or pizza cutter.

Preheat a non-stick skillet over medium heat for about 2–3 minutes.

Cook each farl in the skillet for 3–4 minutes on each side until golden-brown.

Remove from skillet and serve warm, optionally with butter or breakfast items.