Scalloped Ham and Potatoes

A plain layered bake that depends on two things: thin potato slices and enough milk to keep them submerged. The Delineator's temperature range is already given in Fahrenheit, which dates it to the era when home ovens had usable thermostats.

• The hinge: slice thin and keep them coveredCut the potatoes about 1/8 inch thick, ideally on a mandoline, and press each layer flat so the milk covers the top. Any potato standing above the liquid will dry out and stay hard while the rest goes tender.
• Raw smoked hamThis means uncooked cured and smoked ham, what a butcher may sell as raw gammon; note that most supermarket smoked ham steaks, like deli ham, are already fully cooked and will turn stringy over 90 minutes. If that is all you have, add it in the last 30 minutes.
• TemperatureSplit the difference at 375F. At 400F the milk will scorch at the edges before the centre potatoes soften, unless you cover the dish.
• Cover, then uncoverFoil for the first hour keeps the surface from skinning over and the milk from boiling hard and breaking; the last 20 minutes uncovered gives the browned top. Whole milk holds together better than skimmed, and replacing a half cup of it with cream makes curdling much less likely.
• Flour quantityThe recipe gives none. About a tablespoon dusted over each potato layer -- 3 to 4 tablespoons in total for a 2-quart dish -- is enough to thicken 3 cups of milk into a sauce rather than leave it watery.
• SaltNone is called for, correctly: smoked ham carries plenty. Season the potato layers with pepper only and taste before adding any salt at the table.
• Dish and yieldA 2- to 2 1/2-quart baking dish holds six medium potatoes and a pound of ham comfortably. It serves four as a main course, six alongside something else.
• RestingLet it stand 10 minutes out of the oven. The flour-thickened milk sets slightly and the portions lift out instead of sliding apart.