Potato cakes. Only thing my dad could ever cook.
Put tbsp butter into bowl (cereal sized) of mashed potato. Microwave for 1 minute to melt butter/warm potato and mix butter in. Add flour (about half as much as potato) - you want to form a stiffish dough. Make into "burgers" and fry or griddle. My kids love these served with a dollop of pesto or just spread with butter.