Lumpy béchamel: 3 simple tips to get a perfectly smooth sauce

Lumps form when flour does not mix properly with milk, particularly if the milk is poured in all at once, whisking stops, or the heat is too high. For a few small lumps, taking the pan off the heat and whisking vigorously for one to two minutes may be enough. An overly thick béchamel can be loosened by gradually adding warm milk, then returned to low heat. If the sauce has stuck to the pan, transfer the unburnt portion to another pan without scraping the bottom; these methods cannot fix a burnt taste.