New England Onion Soup - cooking recipe

Ingredients

2 tablespoons butter
4 large onions, thinly sliced
2 tablespoons flour
2 cups milk
2 cups chicken broth
1 teaspoon salt
1/2 teaspoon pepper
1/2 teaspoon mace
2 egg yolks
parsley, minced

Preparation

Melt butter in a large pot or kettle, add onions and cook until transparent but not brown.
Stir in flour until well blended.
Gradually add milk, stirring until smooth, then stir in broth.
Add seasonings and simmer for 5 minutes.
Beat egg yolks with cream and pour into a soup tureen.
Gradually stir in soup.
Sprinkle with parsley and serve.