Mix two ounces of sifted flour with two ounces of melted butter. Dilute with one quart of boiling water, salted to the extent of one-quarter ounce per quart. Stir briskly to ensure a perfect liaison, and do not allow to boil. Add immediately the yolks of six eggs, mixed with one-quarter pint of cream and the juice of half a lemon. Rub through a sieve, and finish the sauce with five ounces of best fresh butter.

Be careful that the sauce does not boil after it has been thickened.