This is, basically, the way my mother (1902 - 1985) taught me to make scalloped potatoes ---- with a couple of corrections. After sprinkling a layer of potatoes with the flour mixture, it should be dotted with butter so it cooks into a sauce ---- and the onions should definitely be sauteed. Finally, a nice sauce will develop if you pour just milk over the casserole ---- half cream and half milk would be even better. I think the stock is at odds with the rest of the recipe ---- if a chicken flavor is desireable, why not dissolve some bouillon cubes in the milk/cream?
I'm sorry about this, but we really didn't enjoy these potatoes. I made 2/3 of the recipe, but cooked it for the same time, and they were still a bit crunchy, the onion was very crunchy, and the flour had a raw taste to it. I would prefer to increase the cream, decrease the stock and do away with the flour. I liked the topping and I liked the thyme taste.