Maple Marshmallow Fudge

A two-ingredient candy in essence — maple syrup and milk — with marshmallows folded in at the last moment. The whole thing hinges on the thermometer and on when you stop beating.

• Butter the size of an eggRoughly 2 ounces, or 4 tablespoons. Old books measured fats by eye against a hen's egg; the amount is not critical here, as the butter is there for texture and to keep the boil from climbing.
• Soft ball stage235–240°F on a candy thermometer. Test the old way if you prefer: a drop into cold water should form a ball that flattens between the fingers. Undercooked, the fudge will stay soft and may not set firmly; taken much past 245°F it tends to turn hard and crumbly.
• Maple syrupUse real syrup, Grade A dark or the old "Grade B" if you can find it, for flavour that survives boiling. Pancake syrup is corn syrup with flavouring and will not behave the same way, nor taste of maple once cooked down.
• ScorchingMilk and sugar together catch easily. Use a heavy pan at least three times the volume of the mixture — maple syrup with milk foams up hard — and stir until it reaches a boil, then leave it alone until temperature is reached.
• Cooling before beatingThe recipe goes straight from the boil to beating, but fudge beaten while very hot goes grainy. Let it cool undisturbed to about 110°F, then beat until it loses its gloss and thickens. This is the step that decides whether the texture is smooth or sandy.
• Beat and pour fastOnce it starts to set it sets quickly. Have the buttered pan and the cut marshmallows ready before you begin beating, and pour the moment the mixture holds a ribbon.
• MarshmallowsMarshmallows sold today are generally smaller than the large ones a recipe like this expects you to cut up; halved miniatures work. They will melt partway into the hot fudge; scattering rather than stirring keeps distinct pockets.
• Pan and yieldAn 8-inch square pan yields roughly 36 pieces. Score into squares while still warm and cut through once cold.