Cut the melon(s) in half, remove seeds and scoop out about 16 small melon balls and set aside. Remove the remainder of the melon flesh and cut into pieces. Heat the butter in a pan and sauté the melon pieces for around 4-5 minutes. Add the veal stock and seasoning to taste, cover and allow to simmer for 15 minutes. Then remove from heat and pass through a fine sieve or process until smooth. Pour the melon soup back into the saucepan and, over a moderate heat, stir in the cream (do not allow to boil), together with the well-beaten egg yolks and stir constantly. Remove from heat and allow to cool. Chill for a couple of hours. Stir in the sherry just before serving.

When served, add about 4 melon balls to each individual soup dish and garnish with the chopped chervil and cured ham.