"Optional ingredients" are additional items or substances that you can choose to use or add to a recipe or product, but they are not necessary or required. Full definition
You can also add a variety of optional ingredients in order to customize these healthy breakfast cookies for you and your family. (multitestingmommy.com)
There are a number of optional ingredients in the crumble, but it tastes just as good with the minimal ingredients as well. (sweethealthyliving.com)
You can add optional ingredients to customize it: honey, cinnamon, vanilla, nutmeg, etc.. (maryvancenc.com)