In France this vanilla custard sauce recipe is called crème anglaise, or English cream. Frequently when serving a cake, the French will not add any frosting or icing to it. Instead they will serve a pitcher of crème anglaise along side and this is poured on top.
The Tricky Part
Making crème anglaise is just a little tricky. If you heat the sauce too much or too quickly, the egg yolks will cook into little clumps. This is called curdling and most people don't like a lumpy sauce.
What to do if your sauce curdles despite your best efforts? You can either immediately pour it into a blender and try blending it until smooth (watch out for hot splatters), or pour it into an empty bottle, cap it, and shake away.
In France, this custard sauce recipe is usually made with just a little sugar, but you may want to add just a bit more to this recipe if you like things really sweet. I make this recipe with a combination of heavy cream and milk, but you can also make it with just milk or half and half depending on how rich you want it.
If you can, do make this custard sauce recipe with a vanilla bean. It will have a much nicer flavor. Vanilla beans are expensive and it's nice to get all the use we can from them. So if you wish, rinse the shell, dry it and use it to lightly flavor a canister of sugar. You may be interested in buying vanilla beans in bulk (available on Amazon for example). Because they are light weight, you may even save money by mail ordering these.
In a heat resistant mixing bowl, stir together the egg yolks and the sugar with a wooden spoon until well combined. The sugar should be somewhat dissolved in the yolks but you don't want to add a lot of air.
Place the milk and cream in a medium sized sauce pan. If you're using a vanilla bean, slit it lengthwise and scrape out the seeds, by pressing firmly along the length with the back of a knife. Add the seeds and the bean pod to the milk. Place the sauce pan on medium heat and warm the milk just below the boiling point (the milk will start to form bubbles on the edges of the pan and it will become steamy just before it boils.)
Remove the sauce pan from the heat and stir just a couple of tablespoons of the hot milk into the eggs and sugar mixing well the whole time. Then gradually add the rest of the milk, stirring the whole time. Return the mixture to the sauce pan and place on low medium heat.
Heat the sauce until it thickens, but do not boil or the yolks will curdle. The sauce is done when it stays on the wooden spoon without dripping (this takes about five minutes, but will depend upon your pan and burner). You can run your finger on the back of the wooden spoon and if the track remains without drips, the sauce is done.
As soon as the sauce is thickened, immediately remove from the heat. Pour the sauce into a heat resistant bowl (you can pour the sauce through a strainer to remove the vanilla bean and any clumps). Stir in the vanilla extract if that is what you are using, then cover the sauce with plastic wrap, placing the wrap right on top of the sauce. Refrigerate to desired serving temperature.
Flavor Variations: Stir in 1 tablespoon of your favorite liqueur after the sauce has cooked. Try Grand Marnier,
cognac, or rum.