Boil the potatoes until tender. Drain and mash with the butter.
Mix the flour, salt and baking powder and stir into the warm mash to make dough.
Turn on to a floured board (make sure the board is well floured as the dough can be sticky). Roll out to 6mm (1/4 in) thick. Cut into circles (about 15cm / 6 in) and then into quarters. Prick with a fork.
Heat a large heavy frying pan with a little oil. Cook for approx 3 to 4 mins on both sides until golden brown.