Cheesy, Savory, Tasty

Two side dishes I remember from my childhood are scalloped potatoes and au gratin. What’s the difference you ask? Au Gratin has cheese and scalloped does not. They are both made with thinly sliced potatoes, cream sauce, and are baked. We’re adding ham and green onions to make this ham au gratin potato recipe.

potatoes in a bowl, green onions on the table, ham on a plate, butter, spices, heavy whipping cream, and shredded cheese in bowls

You can make au gratin from a box… or with just a few steps, make an even better homemade ham au gratin potato version from scratch. And ham au gratin potatoes isn’t just a side dish. Hearty, creamy, and packed with potatoes and ham, I would even consider this dish a main course.

What You Need to Make Ham Au Gratin Potatoes

Potatoes – I even surprised myself at how few potatoes this dish requires to fill an 8×8 casserole dish. You need just 4 to 5 medium Russet potatoes. A Russet potato will hold up in the heat.
Ham – I used a bit of ham from a whole ham and will save the rest for sandwiches, and eventually ham and bean soup. You can also buy sliced ham or go right for the super convenience by purchasing diced ham.
Cheese – I really like the super sharp white cheddar. You’ll need 2 cups shredded or 8 ounces that you can grate yourself.
Green Onions – Add a bit of color and flavor with thin sliced green onions.
Heavy Cream – Cream will add a rich, creamy texture. Use corn starch to ensure the sauce thickens.
Seasonings – Dry mustard, Old Bay, fresh ground black pepper, and a bit of salt is all you need. Old Bay is salty as is the ham, but the potatoes will need the extra sodium to give them flavor.

pouring heavy whipping cream into a bowl

corn starch, and cream in a bowl with a whisk with spices in a small bowl

dried mustard, paprika, salt, pepper, corn starch, and cream in a bowl with a whisk

How To Make Ham Au Gratin Potatoes

Preheat the oven to 400 degrees F. Then, start by making the sauce. To make the sauce thick, we need to use a little corn starch. I prefer corn starch over flour whenever possible as a thickening agent because it doesn’t leave an after taste like flour sometimes can.

The secret to the corn starch is that it needs to be mixed with a cold liquid, then heated to thicken. Mix the corn starch with 1/4 cup of the cream until well blended and smooth.

Then, add the corn starch slurry to the rest of the heavy whipping cream. Add the salt, pepper, dried mustard, and Old Bay.

sliced ham and cut diced ham on a cutting board

Next, if you are using ham slices, cut them into cubed pieces. Trim and thin sliced the green onions.

Lastly, rinse and give your potatoes a good scrub. Then, if needed to fit in your food processor, cut the potatoes in halves lengthwise.

potatoes in a colander with a scrub brush

Thin slice the potatoes using a chef’s knife, mandoline slicer, or a food processor with a mandonline blade attachment. I have a small 3 cup food processor with the blade option, and I love it. The drawback is that the potatoes need to be cut in half to fit in the chute of the food processor. The result is half-moon slices rather than full circles.

whole potatoes and potatoes cut in half on a cutting board

sliced potatoes in a large white pie pan

Using a paper towel, smear butter over the sides and bottom of the casserole dish. Next, spread 1/2 of the potato slices on the bottom of the dish. Sprinkle over half of the ham and half of the green onions. Then, spoon over half of the sauce.

butter smudged in a blue casserole dish with tops in bowls around the dish

ham, green onions, and potatoes in a buttered blue casserole dish with extra toppings in white bowls

pouring sauce of ham, green onions, and potatoes

Finally, press the layer down to compress the potatoes before sprinkling on half of the cheese. Repeat this layering with the remaining potatoes, ham, green onions, sauce, and cheese.

first layer of the ham au gradin with cheese potatoes

second layer of ham au gratin potatoes with a pile of cheese on top

Cover the casserole dish with foil. Be sure to tent the foil a bit so that it doesn’t stick to the cheese. Bake for 45 minutes. Then, uncover and bake for another 30 minutes or until the potatoes are tender and the top is bubbly.

final ham au gratin potatoes in a blue casserole dish before being placed in the oven

final ham au gratin potatoes in a blue casserole dish after baking with the foil on top

final ham au gratin potatoes in a blue casserole dish after baking with the foil removed

Tips, Tricks, & FAQs

Potatoes. Feel free to peel your potatoes before using them. I also think this is a fantastic recipe to use up potatoes that have started to age a big, a little wrinkly, maybe they have a few eyes that can be gently removed or cut out. Don’t waste. And, since the potatoes are sliced and covered in a sauce, all those imperfections will be covered.
Substitutions. This recipe calls for green onions, but you could use shaved sweet onions, shallots, maybe try mashed garlic and bacon… Swiss cheese instead of sharp. We’re veering off the path from a traditional au gratin, but that’s ok! Use what’s in the refrigerator or what sounds tasty.
Tasty Toppers. Melt 3 Tablespoons of butter over low heat. Mix in 2 cups of breadcrumbs, a dash of salt and dried herbs. After removing the foil, spread the breadcrumb mix over the potatoes and bake for the remaining 30 minutes uncovered.
Prep the Night Before. Save some time and prep this dish over the weekend and store it for a weeknight dinner, or the night before. Then, save the baking for the day you want to serve up your savory, cheese, potato casserole.
How to Store and Reheat Au Grain? I’ll be honest, I usually keep something like a casserole in the casserole dish and cover it with foil. Then it’s ready to pop back in the oven to reheat. You can also transfer the casserole into storage containers, then back into an oven or microwave safe dish to reheat. I would keep leftovers for 2-3 days.