User defined input form

Is there a way to have the user define the input form? For example, if I want the build a website that lets users store recipes and I want them to input that info through a form, how would I allow them to add new text entry for each type of sweetener they used? So the workflow would be user 1 would click to create a new recipe for cake and add an entry in the sweetener section for # of white sugar and # of brown sugar. User b might use 3 different kinds of sugars and user c could use 5 kinds…