Appealing even to those who think they don’t like spinach.
Melt 4 tablespoons butter in saucepan and saute onions until tender. Add spinach and cook over low heat 5 minutes. Sprinkle with flour and stir over low heat until blended. Remove pan from heat and combine egg yolks and cream. Add ½ cup of hot stock to egg mixture, blend with whisk, and return mixture to soup. Reheat over low heat, stirring gently; do not boil. Remove from heat. If desired, stir in 1 to 3 tablespoons butter. Garnish with diced sweet red pepper or finely chopped parsley.