Put the asparagus peels and end pieces in a saucepan, add 1 liter of poultry stock, as well as sugar, salt, pepper and the lemon juice. Let everything simmer for about 30 minutes over a low flame. Now drain the asparagus stock with a sieve and collect it.
Melt the butter in the pan, add the flour and stir with a whisk to a smooth roux. Now add the asparagus stock to the roux, ladle by ladle, while stirring with a whisk. Mix the cream with the egg yolk in a bowl and stir slowly into the soup, finally season with freshly grated nutmeg and Worcester sauce.