Molasses Sauce

A four-ingredient boiled sauce that behaves like a soft caramel. The whole thing depends on how hard and how long it boils.

• The hinge: watch the boil, not the clockTen minutes at a hard rolling boil can take molasses toward candy stage, so it will set firm as it cools. Keep it at a steady low boil in a heavy pan and judge by eye: pull it when it coats a spoon and drips in a thick ribbon, which may well be short of the full ten minutes.
• Molasses to useLight or dark unsulphured molasses is what this wants. Blackstrap is far more bitter and mineral than the table molasses of the period and will overwhelm the apples.
• Butter and saltButter of the period was often salted for keeping; with unsalted butter you may want a scant quarter teaspoon of salt rather than a bare pinch. Stir the butter in off the heat if you want the sauce glossy rather than slightly separated.
• The vinegar is not optionalVinegar cuts the flatness of boiled molasses; cider vinegar is the likeliest sort here. A tablespoon in a cup reads as brightness, not sourness.
• Pan choiceMolasses scorches readily. Use a heavy-bottomed saucepan at least three times the volume of the sauce, since it foams up sharply as it comes to the boil.
• Yield and servingAbout one cup, enough for six servings. Serve warm over apple dumplings, steamed apple pudding or brown betty; it thickens considerably as it cools and can be loosened with a spoonful of hot water.