Potatoes Au Gratin

A three-line entry that assumes you have just read the boiled-potato recipe above it and know how a cream sauce is built. Filling in those blanks gives a straightforward creamed potato gratin.

• "Cook as above"The instruction refers back to the preceding potato entry, so the cubes are simply boiled until a knife slides in easily; the method and timing belong to that entry, not this one. Drain them well and let the steam dry off, or the sauce will thin out.
• Cream sauce, one pintThe recipe gives no proportions. A medium white sauce is conventionally about 2 tablespoons butter and 2 tablespoons flour to each cup of milk, cooked until it coats a spoon. A pint of sauce to two and a half cups of potato is a generous ratio; it should be thick enough to hold the cubes, not pool around them.
• "Cream cheese" in 1920This means a fresh soft cheese of the Neufchatel type, sold loose or in foil, not the stabilized gum-thickened brick of today. Modern block cream cheese works, but let it come to room temperature and beat it into the hot sauce off the heat so it melts smooth instead of curdling into strings.
• The gratin the text leaves outNothing here browns, yet the title promises a crust. Turn the sauced potatoes into a buttered shallow dish, scatter buttered crumbs or grated cheese over the top, and give it 15-20 minutes at 400F until the surface blisters and colors.
• Potato choiceWaxy or all-purpose potatoes hold their cube shape through boiling and baking. Russets will slump and thicken the sauce with their own starch, which is fine for a puree but loses the point of cutting cubes.
• SeasoningThe recipe gives none. Salt the cooking water, then taste the finished sauce: soft cheese mutes salt, and white pepper, a scrape of nutmeg or a little grated onion are all worth considering.
• YieldTwo and a half cups of potato with a pint of sauce serves four as a side dish, or three if it is standing in for the main course of a meatless supper.