Saute the green onions in butter until golden. Add the garlic, celery, salt and pepper to taste, and chicken stock. Simmer, covered, about 15 minutes, or until the celery is just tender. Stir together the egg yolks, cream and Madeira, and add to the celery. Continue to cook over a low flame, stirring constantly until the sauce thickens. Do not let it boil. Sprinkle with the chopped dill.