Dress, clean, and cut in pieces for serving, two chickens. Cook in a small quantity of water with eighteen tiny young onions. Remove chicken to serving-dish as soon as tender, and when onions are soft drain from stock and reduce stock to one and one-half cups. Make sauce of three tablespoons butter, four tablespoons flour, stock, and one-half cup heavy cream; then add yolks three eggs, salt, pepper, and lemon juice to taste. Pour sauce over chicken and onions.