1. Peel potatoes and onions.
2. Cut potatoes in fairly small cubes and roughly chop the onions.
3. Butter a 1-litre/2-pint pie dish.
4. Mix potatoes and onions with seasoning and nutmeg in the dish.
5. Add the stock and pour melted butter over the top.
6. Cover with foil and bake in a moderately hot oven (190°C, 375°F, Gas Mark 5) for 35 minutes.
7. Take off the foil and add a little more stock if potatoes have absorbed it all. Continue cooking, uncovered, for about 15 minutes, until vegetables are tender and browned on top.
8. Serve hot, sprinkled with chopped parsley.