Vanilla Sauce (Teaspoons butter substitute)

A thin pouring sauce for puddings, built like a sweet white sauce. The whole thing takes about five minutes once the liquid is hot.

• "Butter substitute"This means margarine or another vegetable shortening sold in place of butter when butter was scarce or expensive. Use butter or a stick margarine; the quantity is small enough that either works.
• The fat-flour-sugar pasteTwo teaspoons of fat will not absorb a tablespoon and a half of flour into a smooth roux, so expect a crumbly mixture rather than a paste. Rubbing it together well with the fingers, or working it with the back of a spoon, is what keeps the sauce from going lumpy.
• Add the liquid graduallyPour the hot milk and water in a little at a time at first, stirring to a smooth slurry before the rest goes in. Dumping it all at once onto a low-fat roux is the usual cause of lumps here.
• Why boil two minutesFlour-thickened sauces taste raw and pasty if pulled off the moment they thicken. Two minutes at a bare boil, stirring, cooks out the starch. Keep the heat moderate so the milk does not catch.
• Brown sugarLight or dark both work; dark gives a molasses note that reads almost like butterscotch. Pack it when measuring.
• Vanilla goes in lastAfter the boiling, as written. Vanilla extract is alcohol-based and its aroma cooks away quickly, so it is best stirred in once the sauce is off the boil.
• Yield and consistencyRoughly 1 1/2 cups, going by the equal measures of water and milk; enough for about six small servings alongside a pudding or gingerbread. It should coat a spoon thinly, and it thickens as it cools, so loosen with a spoonful of milk if it stands.