Directions

1. Cook the onions in 4 tablespoons butter until soft. Stir in the flour and cook over low heat for 4 minutes without browning. Add the broth, blending it completely with the flour. Add the parsley sprigs, bay leaf, and thyme and simmer for 20 minutes.
2. Melt remaining 4 tablespoons butter in a large pan. Toss the mushrooms in the butter with salt and lemon juice and cook 5 minutes. Add the mushrooms to the broth and simmer 5 minutes. If not to be used immediately, set aside.
3. Reheat to a simmer. Beat the egg yolks and cream until blended. Stir a cupful of the hot coup into the cream mixture. Add the cream to the soup and heat to below the simmer. (If the soup simmers, the yolks will curdle.) Taste for seasoning. Serve immediately, garnished with chopped parsley.