Cheesy Scalloped Potatoes and Ham Casserole (potato ham au gratin)

This cheesy potatoes and ham bake goes by several names like potato ham au gratin or cheesy scalloped potatoes and ham. Whatever you call it, this homestyle casserole is easy to make, can be assembled in advance and is a treat for the whole family.

ingredients for bechamel, melting butter and dicing onion.

Au gratin potatoes and ham will feed the whole family

When you’re craving a rich, creamy comfort food dinner, this au gratin potatoes and ham casserole is my top pick.

Essentially this is a cheesy scalloped potato recipe with leftover ham that’s topped with extra grated mozzarella and pecorino romano and baked until the crust is burnished and the potatoes are tender. Sound good? I thought so.

Serve this classic ham and potato casserole with my garlic green beans recipe and a simple green salad to round out the meal.

Ingredients:

  • Butter
  • Flour
  • Onion
  • Kosher Salt
  • Dry Mustard
  • Onion Powder
  • White Pepper
  • Milk
  • Fresh Thyme
  • Yukon Gold Potatoes
  • Leftover Ham
  • Grated Italian Cheese Blend or Mozzarella
  • Grated Pecorino Romano
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If you don’t have leftover ham use a ham steak

I like to use leftover baked ham for this recipe, but you can also use smoked ham steaks, cut into cubes. (Smithfield Anytime is one brand).

The only challenge is that these ham steaks are packed in water and can make your casserole very liquidy if you don’t dry the ham very well with paper towels.

How to dry ham steaks

  1. To extract as much liquid as possible, line a baking sheet with several layers of paper towel and place the diced ham in a single layer on top.
  2. Pat the ham dry with more paper towels and let the ham rest in the open air while you prepare the au gratin cheese sauce for the potatoes.
sautéing the onions and adding the flour and spices to make a roux.

What’s the difference between au gratin and scalloped potatoes?

The main difference is cheese. One has it and the other one doesn’t.

Anything “au gratin” has cheese added to it. In French, au gratin refers to “grating” and usually means a dish is topped with some grated or shredded cheese and/or breadcrumbs. For au gratin potatoes the sliced spuds are layered with a simple béchamel or white sauce and grated Pecorino and Italian blend or mozzarella.

Scalloped potatoes don’t have any cheese. See for yourself, neither this plain scalloped potato recipe, or this herb-flecked one has any Instead the richness comes from the silky white sauce.

Adding milk slowly and cooking the bechamel to create the sauce.

Make the cheesy béchamel:

This au gratin ham and potato casserole starts with the cheese sauce and to keep it simple, I combine a few steps for simplicity’s sake by cooking the onions and sauce together.

  1. Melt the butter in a large saucepan.
  2. Add chopped onions and cook until softened.
  3. Sprinkle on the flour and spices and cook until thick and pasty for at least a minute.
  4. Slowly add the milk, stirring constantly and cook until it comes to a low bubble. Cook for about one minute until the sauce thickens.
  5. Remove the pan from the heat and add the Pecorino Romano and Mozzarella or Italian blend.
  6. Stir until the cheese has melted and then add the chopped fresh thyme.

Pro-Tip #1 How to tell if your sauce is done cooking

You can tell when the sauce is thick enough by running a finger across the back of a wooden spoon that has been coated with the sauce. If the line holds and doesn’t run, the sauce is done. Check for this before adding the cheese.

adding grated cheese and fresh thyme to the sauce.

How to assemble the au gratin potato and ham casserole

  1. Spray the casserole dish with nonstick cooking spray and add 1/2 cup of cheese sauce to the bottom. Spread in a thin layer.
  2. Add 1/3 of the sliced potatoes to the baking dish.
  3. Top with 1/2 of the ham.
  4. Add 1/3 of the remaining cheese sauce.
  5. Top with 1/3 of the potatoes, the remainder of the ham and 1/3 of the cheese sauce.
  6. Add the final layer of potatoes and spread the remaining sauce over the potatoes.
  7. Cover and bake.
layering the potato and ham au gratin in a casserole dish.

Pro-Tip #2 Thinning the sauce for the top layer

The longer the cheese sauce rests, the thicker it tends to be.

To get better coverage (into the nooks and crannies of the casserole), I often whisk in a few tablespoons of milk to the remaining sauce before spooning it over the potatoes.

A slightly thinner sauce on top, spreads evenly and helps coat the potato and ham filling. You don’t have to do this, but if the sauce is particularly thick, it’s a good fail-safe method.

Finishing the cheesy scalloped potato and ham casserole with a layer of potatoes and cheese sauce.

You can make the au gratin casserole in advance up to this point and bake it later in the day, but make sure it’s at room temperature before baking, otherwise, it will take longer to cook.

Baking potato ham au gratin

  1. Cover the casserole dish with an oven-proof lid or cover in tin foil.
  2. Bake, covered, in a preheated 375° oven for 45 minutes.
  3. Remove the lid or foil and reduce the oven temperature to 350° and bake au gratin potatoes and ham for 20 more minutes.
  4. Sprinkle on the reserved cheese and bake an additional 10-15 minutes or until the top is golden and bubbly.

Pro-Tip #3 Don’t add the final layer of cheese just yet.

Since this recipe uses sliced raw potatoes, the casserole takes a while to bake. To avoid burning the cheese — don’t add the au gratin topping until the very end of baking.

Gratinée the scalloped potatoes and ham with a layer of grated cheese and cook until browned and bubbly.

Variations for cheesy scalloped potatoes with ham

You can change up this ham and potato casserole by using different types of cheese or other mix-ins. Here’s some of our favorites:

  • Use white or yellow sharp cheddar in the sauce and top the casserole with fresh buttered breadcrumbs.
  • Use leftover turkey, sautéed mushrooms (well drained) and frozen peas for a post-Thanksgiving turkey potato au gratin.
  • Instead of ham, season and brown some ground beef with the onions – and drain it very well. Layer the beef, with the potatoes and cheese sauce (I’d use a cheddar cheese).
  • Crumble blue cheese (gorgonzola or roquefort) between the layers of potato to give a more assertive flavor.
  • Add caramelized onions between the layers of potatoes for a mellow sweetness.
Baked potato ham au gratin with fresh thyme leaves.

Casserole FAQ’s

Can I make the ham and potato casserole in advance?

Yes. Assemble the casserole earlier in the day, or even the night before. Let it come to room temperature before baking.

Can I halve the recipe?

Yes! There’s only two of us most of the time in our house, so I’ll frequently cut this recipe in half for a smaller casserole. Of course you can also make the full recipe and divide it up between two casserole dishes. That way you’ve got one to eat now and another potato and ham bake for later.

Can I freeze the au gratin potatoes and ham?

Yes. You can freeze extras. I like to put them into a freezer and oven safe container and wrap it well with plastic wrap and freezer paper. The frozen casserole should hold up for 2-3 months in the freezer. Defrost before reheating.

How do I reheat the cheesy ham and scalloped potato casserole?

Warm the au gratin potatoes with the lid on the casserole dish (or covered with foil) in a 325° oven for 20-30 minutes or until hot. Remove the lid in the last five minutes of heating.

A serving of cheesy scalloped potatoes with ham on a plate with a fork.
potato and ham casserole with fresh thyme garnish.
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3.48 from 42 votes

Potato Ham Au Gratin

Potato Ham Au Gratin is the ultimate comfort food! Layers of thinly sliced potatoes, diced ham, caramelized onions and a dreamy cheese sauce!
Author: Lisa Lotts
Course Main Course
Cuisine American
Keyword casserole, ham, potato
Prep Time 30 minutes
Cook Time 1 hour 10 minutes
Total Time 1 hour 40 minutes
Servings 8

INGREDIENTS:

  • pounds Yukon Gold potatoes peeled and thinly sliced. (You can also use red skinned potatoes).
  • 1 pound leftover ham diced
  • 1 large onion diced
  • 3 tablespoons butter divided
  • 3 tablespoons flour
  • 1 teaspoon kosher salt
  • 1 teaspoon dry mustard
  • 1 teaspoon onion powder
  • ½ teaspoon white pepper
  • 3 cups milk
  • 1 teaspoon fresh thyme chopped
  • 2 cups shredded mozzarella or Italian blend cheese divided
  • 1 cup freshly grated pecorino romano divided

DIRECTIONS:

  • Place the oven rack in the center of the oven and preheat the oven to 375° F.
  • Spray a 2 quart casserole with vegetable spray
  • In a large saucepan, melt butter over medium heat. Add the diced onions and sweat for 4-5 minutes until the onions are softened and translucent.
  • Add the flour, salt, onion powder, dry mustard and pepper and stir constantly as it cooks and bubbles for about one minute. When there are no bits of dry flour or spices left, add the milk a little at a time, whisking after each addition until the milk is incorporated. Heat the sauce to a boil over medium high heat, stirring constantly. When the sauce begins to bubble cook for an additional minute, then remove from the heat. Stir in the chopped thyme.
  • Add 1½ cups of the grated mozzarella and ¾ cup of the pecorino romano and stir until the cheese is completely melted.
  • Add about a half cup of the sauce to the bottom of the casserole dish and spread evenly in the bottom.
  • Arrange ⅓ of the potatoes, overlapping each other in the bottom of the dish. Sprinkle ½ of the ham cubes over the potatoes.
  • Add ⅓ of the cheese sauce to the potatoes and gently spread with a spatula (doesn’t have to be perfect).
  • Add another layer of potatoes, ham and sauce followed by the remainder of the potatoes and sauce.
  • Cover with a lid or aluminum foil and bake in the oven for 45 minutes.
  • Reduce the heat to 350° and remove the lid or foil. Continue to bake for 20 minutes.
  • Sprinkle on the remaining mozzarella and pecorino romano and bake for an additional 10-15 minutes or until the cheese is melted and browned.
  • Let the casserole cool for about 10 minutes before serving.

NUTRITION:

Calories: 480kcal | Carbohydrates: 35g | Protein: 29g | Fat: 25g | Saturated Fat: 13g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 9g | Trans Fat: 1g | Cholesterol: 87mg | Sodium: 1373mg | Potassium: 952mg | Fiber: 4g | Sugar: 7g | Vitamin A: 481IU | Vitamin C: 30mg | Calcium: 485mg | Iron: 2mg

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23 Comments

  1. 5 stars
    My whole family loved this casserole. No leftovers!

  2. 5 stars
    This is terrific! Two things: I really did caramelize the onions – 20 minutes or so over medium heat, until brown. Also, this would never fit in a two quart casserole – I used a three quart (9 x 13) and it was a nice fit. Oh, one more: I only had shredded cheddar, and it was GREAT!

  3. Kim Sisson says:

    5 stars
    This recipie is delicious !! Try it!! It’s so easy…especially the 2nd time!

  4. Great recipe — I really appreciate the nutritional information. Can’t wait to get more into your site. This was delicious and my husband wants me to throw it into our rotation. Instead of caramelized onions, I thinly sliced a Vidalia with my mandolin, too, and they melted into the dish beautifully. Topped it with fresh green onion and parsley as quick as it came out of the oven. Thanks again!

    1. Thanks for your comment, Jessica — so glad that it worked out well for you and that your husband enjoyed it. If you’re putting it into rotation — do yourself a favor and caramelize a bag of onions — then just parse them out into 1/4 cup or 1/2 cup containers and freeze them — they’ll be ready the next go round.

  5. 5 stars
    You list 1 1/2 cups milk and then say to use 1 1/4 cups milk to make the cheese sauce. I used all 1.5 cups but just wondered which one it should be. Mine looks fine btw!

    1. Good catch, Maria — thank you. I’ve fixed it.

  6. 5 stars
    This was great! We had some left over cooked smoked ham, what an excellent way to use it up. Because I had a lot of ham, I doubled the recipe and made it in a 9×13 casserole dish. I used white russet potatoes and cooked my onions until translucent. I have yet to try carmelized onions, but I know they’d be delicious. Thanks so much for the recipe!

    1. I’m so glad you enjoyed it, Mallory! I’m a big fan of repurposing leftovers like that! Thanks for sharing!

  7. Jackie Cooper says:

    Hi Lisa

    Can I omitt the ham? Also, how thin are these potatoes, 1/16, 1/8, 1/4 etc.

    1. Hi Jackie! Sure you can omit the ham — and cut the potatoes as thinly as you can with a knife — 1/8″ would be good. If you have a mandoline, you can go thinner.

  8. This looks absolutely delicious!! You always make the best looking recipes!

  9. Have I ever told you how much I LOVE potatoes??… cheesy potatoes to be exact. LOVE LOVE LOVE. These look amazing! 🙂

    1. LOL! I’m so glad you like them, Katrina! Next time you’re over….

  10. Oh. my. goodness. That is total comfort food! My family is going to go crazy over this!

  11. Dahn @savor the best says:

    What a great side dish for Thanksgiving! This looks amazing and would be gobbled up in a flash at my Thanksgiving dinner. Great pics too!

    1. We actually had this for dinner with a side salad! Does that make me a glutton?

    1. Thank you, yes I love caramelized onions in this dish — it adds a nice sweet unctuousness!