Use a small butternut squash, approximately 1 lb unpeeled, cut in half and seeded. Green apples should be peeled, cored and chopped.
Combine squash, apples, onions, herbs, chicken stock, bread cubes, salt and pepper in heavy sauce pan. Bring to a boil and simmer uncovered 30-45 minutes. Scoop out flesh of squash and discard the skins. Return pulp to sauce pan. Puree the bisque in a blender until smooth. Return to sauce pan. In a small bowl, beat egg yolks and cream together. Beat in a small amount of the hot bisque, then return to the saucepan. Heat but do not boil.