I am on a quest to make the perfect au gratin potatoes. I can get the flavor pretty much right but I struggle with the consistency. Lately I have been baking them until cooked, cool, and then re-heat - this has helped set them and reduced the runniness but they still aren't perfect.
I am looking for au gratins that cut into a perfect square, and don't slip/slide apart... like in this photo.
Any suggestions on techniques and/or ingredient modifications?