That sounds really iffy. If no one else has tried it, and you give it a shot, please let us know how it goes. I'm not sure if the milk was the culprit, since I've frozen other chowders successfully. I think the cornstarch might be the problem. I'd love to hear what others say, but my own personal experience with foods thickened with cornstarch is that they don't always retain their consistency well when reheated or if frozen. I use white flour in my chowder