It should be cooked so as to retain its bright green color and not sent to table, as it so often is, of a dull brown or olive color; to retain its fresh appearance, do not cover the vessel while it is cooking.
Spinach requires close examination and picking, as insects are frequently found among it and it is often gritty. Wash it through three or four waters. Then drain it and put it in boiling water. Fifteen to twenty minutes is generally sufficient time to boil spinach. Be careful to remove the scum. When it is quite tender, take it up, and drain and squeeze it well. Chop it fine, and put it into a saucepan with a piece of butter and a little pepper and salt. Set it on the fire and let it stew five minutes, stirring it all the time, until quite dry. Turn it into a vegetable dish, shape it into a mound, slice some hard-boiled eggs and lay around the top.
The White House Cookbook (1887).