Peanut Fudge

A three-ingredient fudge that relies entirely on hitting the right sugar concentration, since there is no chocolate or corn syrup to hide behind.

• The hinge: soft-ball stage"Until a soft ball can be formed in cold water" is 234-240F on a candy thermometer, and this is the whole recipe. Under that, the fudge will not set; over it, you get a crumbly, grainy block.
• Pan size and boil-overThree cups of sugar with a cup of milk will climb the sides once it comes to a rolling boil. Use a heavy saucepan holding at least 3 quarts, and stir until the sugar dissolves, then leave it alone.
• Cool before beatingThe instruction to take it from the fire and beat is better done after the syrup drops to about 110F. Beating a boiling-hot syrup gives large sugar crystals and a sandy texture; the wait is what makes it creamy.
• Peanut butterPeriod peanut butter was typically unsweetened and unhomogenised. Natural-style peanut butter behaves closest to it; commercial sweetened brands will push an already very sweet candy further.
• Brown sugarLight brown gives a cleaner peanut flavour, dark brown a heavier molasses note. The recipe does not say whether the cups are packed or loose.
• MilkWhole milk. Skim milk lacks the fat to keep the mixture smooth, and the candy is more prone to scorching without it.
• Pan and yieldAn 8-inch square pan is a reasonable choice; expect a fairly thin slab, with the number of squares depending on how small you cut them. Score while still warm and firm, then cut through once fully cool.
• HumiditySugar candy is unforgiving on a damp day. If the kitchen is humid, cook a degree or two higher rather than longer at a lower temperature.