Here’s a soup to serve in celebration of winter’s end.
Melt butter in soup kettle. Add spinach, watercress, and chervil and saute over low heat until wilted, about 5 minutes. Sprinkle with flour and stir until blended. Add stock and simmer 10 minutes, stirring until smooth. Press mixture through food mill. Return to kettle and heat. In separate bowl combine egg yolk and cream. Add ½ cup hot liquid to egg mixture, blend with whisk, and return to kettle. Stir until blended. Season with salt and pepper.