Sponge custard is a type of regular custard but with a flavour of sponge cake in it. Sponge custard is widely appreciated for its smooth texture and is very popular with children. The ingredients used in making this recipe sponge custard are very easy and basic. Some of the ingredients used in making sponge custard are separated eggs, cream of tartar, cups milk, chocolate-flavored syrup, and unbleached flour. Moreover, you can also add some optional ingredients such as vanilla and Marshmallow fluff or whipped cream to give some flavor.