Custard is a versatile dessert made of dairy, eggs, sugar and thickeners. It has been enjoyed since the middle ages as the basis for French pots de creme and creme brûlée, as well as Spanish flan. You can make a basic custard at home from a variety of dairy options, including milk, half and half and cream. The dairy you choose will affect the custard's thickness and texture.

Half and half is a mixture of milk and heavy cream. It is usually served with coffee, but some custard recipes call for it. In the U.S. commercially produced half and half contains anywhere from 10 to 18 percent butterfat. If you do not have half and half, you can make your own at home. Simply mix equal parts whole milk and heavy cream in a food-safe container such as a mason jar.

Most grocery stores carry both heavy cream and whipping cream. These are both made from the butterfat solids that rise to the top of the milk before it is separated and processed. Heavy cream contains between 36 and 40 percent butterfat suspended in liquid. Whipping cream contains slightly less, around 30 percent butterfat. When choosing cream for your custard, look at the nutritional information printed on the label -- fattier cream will yield a richer custard.

Custard is made by combining eggs and sugar, then drizzling in scalded milk, half and half or cream. Your choice in dairy will determine how thick your custard is and how rich it tastes. Half and half will give you a lighter, thinner custard than whipping or heavy cream. Which you use will depend on your personal tastes and the final dish. If you plan to serve the custard with fruit or berries, consider using half and half. However, if you are making flan or creme brûlée, which are known for their luxuriously rich texture, heavy cream would be a better choice.

If you use custard powder in your desserts, rather than preparing traditional custards from scratch, the same general rule applies. The powder is similar to instant pudding mix, and the directions on the package usually instruct you to mix the powder with milk. If you substitute half and half or even heavy cream, the finished dessert will have more of the rich flavor and texture that's traditionally expected in custard.