Yes, taking some care. You can freeze béchamel sauce in ready dishes as lasagna and pies. If you want to freeze it alone, don't use cornstarch as thickening agent replace with flour. The cornstarch separate of liquid in the freezing process and loses texture when thaw, making a watery sauce.
Make the sauce frying in butter the flour and gradually add milk and follow the chosen recipe. Wait to cool cover with a wrap and refrigerate even warm; then freeze it in an container with no free space. Unfreeze in double boiler.
Durability: 3 months.
Photo of dish with béchamel sauce.