2 handsome potatoes weighing 250g (8¾oz) each (Don’t use new potatoes)
30g (1oz) butter
1tablespoon grated Gruyère cheese
1tablespoon freshly-chopped parsley
1tablespoon freshly-chopped chives
Preheat the oven to 200°C/400°F/Mark 6.
Wash the potatoes under the cold tap, without peeling them, and when the oven is hot cook them for 45 minutes. They are done when you can pierce them easily with a small knife. Remove them, but leave the oven on at the same temperature setting.
Make an incision lengthwise across each potato and remove a wedge 1cm (½inch) across. Scoop out the flesh of each potato with a tablespoon, taking care not to puncture the skin, and leaving a thin layer of flesh.
Mash the pulp in a soup plate with a fork, adding first the butter and then 2tablespoons of the cream. Mix thoroughly and season with salt and a little grated nutmeg and stir in the herbs.
Pile the mixture into the potato shells. Mix the remaining tablespoon of cream, the half egg yolk and the grated cheese in a bowl and spread a tablespoon of this mixture over each stuffed potato.
Put the potatoes back in the oven for 5–10 minutes to glaze to a golden brown and serve immediately.