Basic Vanilla Sauce

In a small saucepan over medium heat, bring the milk to a simmer.

Meanwhile, in a medium bowl, whisk the egg yolks and the sugar together until a ribbon forms when the whisk is lifted from the mixture.

Whisk constantly while slowly pouring the hot milk into the yolk-sugar mixture.

Return the mixture to the saucepan. Over low heat, stir constantly with a wooden spoon until the mixture thickens. Be careful not to overcook or the eggs will scramble. The sauce is finished when you can dip a spoon into it, then draw your finger over the back of the spoon and have a track remain that is almost free of sauce.

Remove the sauce from the heat and stir in the vanilla. Serve, or chill and use later.