Easy Au Gratin Potatoes and Ham

Why You’ll Love This Recipe

• A delicious way to use leftover ham: Turn your Easter or Christmas leftovers into another satisfying family dinner.
• Homemade creamy sauce: A simple onion béchamel sauce brings everything together without canned soup.
• Two kinds of cheese: Monterey Jack and cheddar add plenty of cheesy flavor and melt beautifully.
• A longtime family favorite: I’ve been making this casserole for decades, and it was one of my children’s most-requested dinners when they were growing up.

Ingredient Notes and Substitutions

A complete list of ingredients and exact measurements is in the recipe card below.

• Russet potatoes: Their starchy texture works beautifully in this casserole. Yukon Gold potatoes are another good option. Slice them thinly and evenly so they’ll cook at the same rate. I usually leave the skins on, but peeling is entirely up to you. In my test, my potatoes weighed 1 lb 9 oz and were sliced ⅛-inch thick.
• Ham: Leftover baked ham is my favorite choice, but thick slices of cooked ham from the grocery store work just as well. Cut the ham into bite-sized pieces so it’s evenly distributed throughout the casserole.
• Monterey Jack and cheddar cheese: These cheeses melt beautifully and add plenty of flavor. You can substitute Gruyère, Gouda, Fontina, Havarti, or a shredded cheese blend.
• Butter, onion, flour, and milk: These everyday ingredients make the homemade white sauce that holds everything together. Cook the onions until softened, then whisk in the flour and milk to create a smooth sauce.
• Salt and pepper: Ham and cheese already contain salt, so season carefully. I use unsalted butter and kosher salt, but you may need less salt depending on your ham and cheese.

How to Make Au Gratin Potatoes and Ham

Make the Cream Sauce

1. Melt the butter in a large skillet over medium-low heat. Add the onions and cook for about 5 minutes until they are soft and translucent.

   

2. When the onions are done, sprinkle flour over them and whisk to combine. I use Julia Child’s rule of thumb here for the white sauce, one and one-half tablespoons of flour for every one cup of milk or liquid. Continue cooking the onion and flour mixture until the flour is light golden brown, about one to two minutes.

   

3. Slowly add the milk and continue whisking to prevent lumps. Cook until the sauce has thickened, which usually takes about two minutes. Add salt and pepper, mix well and remove from the heat.

   

Assemble the Casserole

1. Spray a 9-inch square baking dish with non-stick cooking spray or butter the dish. Add half of the sliced potatoes, then half of the cubed ham, and about half of both kinds of grated cheese.

   

2. Pour on half of the sauce. Repeat the next layer with the remaining potatoes and ham, pour the remaining sauce over the top and sprinkle with the remaining cheeses.

   

Bake Until Golden and Bubbly

1. Cover the baking dish tightly with aluminum foil and bake at 350°F for approximately 70 minutes, or until the potatoes are fork-tender. Remove the foil and continue baking for approximately 20 minutes, or until the sauce is bubbling and the cheese is golden brown.
2. Let the casserole rest for 10 minutes before serving.
3. Garnish with chopped parsley and serve.

Sharon’s Tips

• Tested make-ahead option: I assembled this casserole two hours before baking, covered it, and refrigerated it. After letting it sit on the counter while the oven preheated, I baked it covered for 70 minutes, then uncovered for another 20 minutes. I sliced the potatoes ⅛-inch thick, and the casserole turned out beautifully. Baking times may vary depending on the thickness of the potato slices and whether the casserole is refrigerated before baking.
• Slice the potatoes evenly. The thickness of your potato slices makes the biggest difference in cooking time. A mandoline or food processor with a slicing blade makes this easier, but a sharp knife works, too.
• Don’t rush the sauce. Cook the flour with the softened onions for one to two minutes, then gradually whisk in the milk. Allow the sauce to thicken before removing it from the heat.
• Check for tenderness before browning. The potatoes should be fork-tender before you remove the foil for the final baking period. If they’re still firm, keep the casserole covered and give them more time.
• Watch the salt. Ham and cheese can be salty, so I use unsalted butter. If you substitute salted butter, omit the additional salt or adjust it to taste.
• Give it a few minutes to settle. Let the casserole rest for about 10 minutes after removing it from the oven so the bubbling sauce can settle before serving.

What to Serve With Au Gratin Potatoes and Ham

This hearty casserole can be the centerpiece of a family dinner, especially when you’re using leftover holiday ham. I like the idea of serving it with a simple green salad or a lightly seasoned vegetable to balance the rich, cheesy sauce.

For a Southern-style supper, try it with Easy Southern Black-Eyed Peas or Southern Fresh White Acre Peas. Both are delicious alongside ham and potatoes.

Au Gratin Potatoes and Ham FAQs

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Final Thoughts

This old-fashioned casserole has been a favorite in my family for generations, and it’s still one of the first recipes I think of when there’s leftover ham in the refrigerator. I hope your family enjoys it as much as mine has over the years!