600ml stock, preferably one that goes with whatever it is you're having with this)
Huge lump of butter
Peel and slice the potatoes quite thinly. Put them in a deepish(i.e. one that will fit them) frying pan and add the butter and stock. Simmer until reduced and crumbling apart. If you need to top up part way through with some more water. Mash any potatoes that haven't already fallen apart, season and serve.