Cut the leaves from two quarts of spinach, wash them thoroughly and throw them in a per fectly dry soup-kettle; stand the kettle over the fire and stir constantly for fifteen minutes until the spinach is wilted and cooked. Drain, saving the water. Chop the spinach very fine, then press it through a purée-sieve; add it to the water and a small onion grated; put this with a quart of milk in a double boiler. Rub a rounding tablespoonful of butter and two of flour together, add them to the milk, stir until smooth; add a level teaspoonful of salt, a saltspoonful of pepper, and if you have it, half a teaspoonful of beef extract that has been dissolved in a little of the soup. Strain at once into a tureen, and serve with croutons or breadsticks.