Given a paragraph about cooking, and a set of conversational question answers about the paragraph, generate a relevant question to the topic of the paragraph. The paragraph has the prefix 'CONTEXT:'. Each conversation question has a prefix `Q:` followed by the answer prefix `A:`.

CONTEXT: You don't need to defrost it, you can add cold roux directly to a boiling liquid. To avoid lumps from the roux, most cooks suggest you either add cold roux to a hot sauce, or cold liquid to hot roux. If you heat the roux gradually with the liquid you may get lumps, and don't get a good impression of how much thickening is going on until it heats fully.  <sep>  Q: I like preparing a large quantity of Roux and pouring them in ice trays to keep them in the freezer. How would I defrost them? A: You don't need to defrost it, you can add cold roux directly to a boiling liquid 
How would I use it in something like mac and cheese?