What is the difference between scalloped potatoes and au gratin?
Generally speaking, scalloped potatoes lean more “creamy sauce and potatoes,” and au gratin leans more “cheese layered in and browned on top” (sometimes with breadcrumbs). In real kitchens (and depending on where you grew up), the lines get blurry fast. This recipe happily lives in the “scalloped, but with cheese because we have priorities” category.
Do I have to peel the potatoes?
Nope. If you like a smoother, more classic texture, peel them. If you want less prep and a little rustic vibe, scrub well and leave the skins on. Russets have thicker skins than Yukon Golds, so that is personal preference.
How thin should I slice the potatoes?
Aim for about 1/8 inch. If they are thicker, they take longer and the sauce can reduce too much before the potatoes are tender. A mandoline makes this fast and consistent, but a steady knife hand works too.
Can I use different ham?
Yes. Leftover holiday ham is perfect. Thick-cut deli ham works. Smoked ham adds a little extra punch. Just avoid super sweet glazed ham unless you want that sweet-savory thing happening.
Why is my sauce watery?
Usually one of three things: the potatoes were sliced too thick, the casserole did not bake long enough, or it was served immediately. Let it rest 10 to 15 minutes so the sauce settles and thickens.
Can I make this ahead?
Yes. Assemble, cover, and refrigerate up to 24 hours. Tip: make sure the potatoes are well coated and tucked under the sauce so they do not dry out or discolor. Let the dish sit at room temp for 20 to 30 minutes before baking, or add 10 to 15 minutes to the covered bake time.
How do I keep the cheese sauce from getting grainy?
Do not boil the sauce after the cheese goes in. Turn off the heat first, then whisk in the cheese until smooth. Gentle heat equals creamy sauce. Aggressive heat equals regret.