Ham and Scalloped Potatoes with a Cheddar Sauce
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The year we skipped the foil, the top went dark before the middle softened, and we ate every bite anyway. Now it bakes covered, then bare, with thin potatoes, diced ham and a smooth cheddar sauce. Rest it ten minutes.
The short version
Make a quick cheddar sauce with a flour-and-butter base, layer it with thin-sliced potatoes and diced ham in a 9×13-inch dish, and bake covered at 375°F for 40 minutes, then uncovered for 20 to 25. Rest 10 minutes before serving.
What makes ours better
the tricks Nonna pretends she never taught me
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Thicken the sauce with a roux before baking. A raw cream bath can curdle or turn thin and greasy. A flour-and-butter base keeps the sauce smooth and creamy through the whole bake.
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Slice the potatoes thin and even, about ⅛ inch. Thick or uneven slices finish at different times, so some are crunchy while others turn to mush. A mandoline makes it quick.
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Cover with foil first, then uncover. The covered bake steams the potatoes until tender. The final uncovered stretch browns the top without drying the middle.
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Shred the cheese from a block. Pre-shredded cheese is coated in starch that keeps the sauce grainy. A block melts smooth, and it takes a minute.
What you need
the cast, in order of appearance
- Unsalted butter3 tablespoons
- Yellow onion1 medium
- Heavy cream1 cup
- Sharp cheddar2 cups
- Grated Parmesan½ cup
- Dried thyme½ teaspoon
- Yukon Gold potatoes3 pounds
- Diced cooked ham2 cups
The sauce
The layers
yes, all of the butter
Steps
nobody opens the oven door. looking at you, Dad.
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Heat the oven, prep the dish
Set a rack in the middle of the oven and heat it to 375°F. Butter a 9×13-inch baking dish. Slice the potatoes ⅛ inch thick and keep them in a bowl; they're fine for an hour or so.
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Soften the onion
Melt the butter in a large saucepan over medium heat. Cook the onion, stirring, until soft and translucent, 3 to 4 minutes. Add the garlic and cook 1 minute more.
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Make the roux and sauce
Sprinkle in the flour and stir for 1 to 2 minutes, until it smells like toasted bread. Whisk in the milk and cream a little at a time until smooth. Simmer, stirring, until slightly thickened, about 5 minutes.
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Melt in the cheese
Take the pan off the heat. Stir in the cheddar and Parmesan a handful at a time until smooth, then add the salt, pepper and thyme. Taste; the ham will add more salt later.
Take it off the heat before the cheese goes in. Boiling a cheese sauce makes it grainy.
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Layer the casserole
Spread half the potatoes in the dish in an even layer, then scatter over half the ham and pour over half the sauce. Repeat with the rest of the potatoes, ham and sauce. Press down lightly so the potatoes are mostly covered.
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Bake covered
Cover tightly with foil and bake for 40 minutes, until the potatoes are nearly tender when a knife slides in.
About 40 min. Cook mode has a timer for this step.
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Bake uncovered
Remove the foil and bake 20 to 25 minutes more, until the top is golden and the sauce bubbles at the edges. A knife should slide through the potatoes with no resistance.
About 20 min. Cook mode has a timer for this step.
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Rest and serve
Let the dish stand for 10 minutes so the sauce thickens and the slices hold together. Sprinkle with parsley and serve.
About 10 min. Cook mode has a timer for this step.
Good to know
things I learned the hard way, so you can skip that part
- Yukon Gold potatoes stay creamy and hold their shape. Russets work and give a softer, more melting result.
- To make ahead, assemble the casserole, cover, and refrigerate up to a day. Take it out 30 to 60 minutes before baking, and add 10 minutes to the covered time.
- The ham is usually salty, so don't add extra salt to the layers. Taste the sauce and adjust only if needed.
- Storage. Fridge, 4 days. Freezer, up to 3 months, though the sauce is a little looser after thawing. Reheat covered at 350°F for 20 to 25 minutes, or single portions in the microwave.
Questions, answered
the questions my cousins text me
Why are my scalloped potatoes still hard?
The slices were too thick or the dish was uncovered too early. Slice ⅛ inch thin and bake covered for the first 40 minutes. If they're still firm, re-cover and bake another 10 to 15 minutes.
How do I keep the sauce from curdling or looking greasy?
Use a flour-and-butter base, keep the cream at a simmer and not a boil, and add the cheese off the heat. Shredding your own cheese helps too.
Can I use leftover ham?
Yes, that's the best use. Dice any cooked ham, including leftover holiday ham or a ham steak. Two cups is the right amount, about 12 ounces.
Do I need to peel the potatoes?
No. Yukon Gold skins are thin and soften in the oven. Peeled slices look more uniform, but either is fine.
Can I make it ahead?
Yes. Assemble up to a day ahead, cover, and refrigerate. Let it sit out for 30 to 60 minutes and add about 10 minutes to the covered bake.
What's the difference between scalloped and au gratin potatoes?
Scalloped potatoes bake in a creamy sauce, and au gratin potatoes are topped with cheese or breadcrumbs. This recipe is both, since the cheese is in the sauce and browns on top.
From the table
Made it? Tell me how it went, and who went back for seconds when they thought nobody was looking.
Made it?
be honest. I can take it. probably.
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Published October 29, 2026.