To serve 6:
1kg of pumpkin slices
2 large potatoes
1 egg yolk
3 sprigs of chervil
A pinch of nutmeg
Salt and pepper to taste
Peel the pumpkin and the potatoes and cut them into small cubes.
Heat them with a small amount of butter in a saucepan for a few minutes.
Add water to the pan, just enough so that the contents (potatoes, pumpkin) are covered. Add salt and pepper to taste and simmer for about 30 minutes, stirring occasionally.
In a separate bowl, mix the cream, the egg yolk and the pinch of nutmeg. Take the pan with the potatoes in off the heat and slowly add the cream mixture to the pan. Stir until you have achieved a velvety consistency. Add more seasoning if necessary.
Divide into bowls and just before serving, add the chopped chervil.