In a large mixing bowl, combine your cooled mashed potatoes, all-purpose flour, salt, and melted butter. Stir gently until the mixture forms a soft dough, taking care not to overwork it.

Transfer the dough onto a lightly floured surface and begin kneading it gently for about 1 minute until it’s smooth.

Roll the kneaded dough into a circular shape about 1/4-inch thick. Use a sharp knife to slice the dough into quarters.

Preheat a non-stick skillet or griddle over medium heat for about 3 minutes.

Carefully place the cut farls in the hot skillet. Cook for 3-4 minutes on each side until golden brown.

Once both sides of the farls are perfectly browned, remove them from the skillet and serve warm.