2) Heat a medium non-stick skillet over a medium heat. Add the potatoes and spread to evenly fill the skillet. Cook the potato cake, adding a few nut size bits of the remaining butter around the edges until the underside is crispy brown, about 10 minutes.
3) Reduce the heat to medium-low and flip the cake by sliding onto a plate and then inverting back into the pan. Cook, adding the last of the butter as before around the edges, until golden brown and the potatoes are cooked through, about 10 minutes more. Serve immediately.