Gruyere potatoes au gratin is a cheesy potato side dish that's perfect for your next holiday meal. Thin sliced potatoes are baked in a creamy herb sauce with melty gruyere cheese.
Gruyere potatoes au gratin is the ultimate comfort food side dish. Made with sliced potatoes, freshly shredded gruyere cheese, and a creamy herb sauce - this will be a new family favorite.
Gruyere cheese is smooth, creamy, and has a lightly salty and nutty flavor. These potatoes pair well with ham, turkey, beef roast, and chicken - the perfect addition to your next holiday meal!
Serve at your next family dinner, Easter, Christmas, or Thanksgiving. This recipe is easy to double or half, and can be made ahead and reheated the next day.
Ingredients and substitutions
I recommend russet potatoes or yukon gold potatoes for this recipe. They're both easy to find at your local grocer and are available year round.
Both potatoes hold their shape when baked because of their high starch content. Plus, the starch will help your creamy sauce thicken up while baking.
Thyme can be substituted with dried rosemary or oregano. Or, use dill like in my Simple Dill Scalloped Potatoes recipe for a bright, springtime flavor!
Can't find gruyere cheese? Swiss cheese is similar in flavor, though a bit milder. Sharp cheddar cheese and monterey jack cheese would also make great substitutions.
No matter what cheese you choose, I highly recommend freshly grating your own cheese from the block. Pre-shredded bagged cheeses are usually coated in anti-clumping powders that become grainy when melted. Grating cheese fresh from the block will prevent this issue.
How to thinly slice potatoes
My secret to perfectly sliced potatoes? Use a mandoline slicer, like this version on Amazon.
The best part about using a mandoline is that you can set it to slice your potatoes at ⅛" and every slice will come out perfectly. This is important because your dish will cook through properly, without any uncooked or overcooked areas.
If you don't have a mandoline, don't fret! Many times your food processor will have an attachment to slice vegetables. Or, check the sides of your box cheese grater - one side may have a vegetable slicer.
If all else fails, carefully slice your potatoes using a chef's knife. This option will likely be the most time consuming, but will work.
Potatoes au gratin can be assembled a day ahead and stored in the refrigerator overnight before baking. Cover your casserole dish with plastic wrap, pressing down to keep out as much air as possible. Exposed potatoes may discolor slightly overnight.
While your oven is preheating, bring your casserole to room temperature on the counter top, then bake as directed in the recipe card.
Your casserole can also be baked, cooled, and stored in the refrigerator overnight. To reheat an entire baked casserole, preheat your oven to 350 degrees Fahrenheit while your casserole comes to room temperature on the counter top. Cover and bake for 30 minutes, or until heated through in the center.
Gruyere Potatoes Au Gratin
- 3 pounds russet potatoes, or yukon gold
- 1 small onion, diced
- 4 cloves garlic, minced
- ¼ cup unsalted butter
- ¼ cup all-purpose flour
- 8 ounces chicken broth
- 16 ounces milk
- 1 ½ teaspoons salt
- ¾ teaspoon pepper
- ½ teaspoon dried thyme
- 2 cups freshly shredded gruyere cheese
- Preheat oven to 350 degrees. Lightly grease a 9x13 casserole dish and set aside.
- Peel potatoes, rinse, and slice to ⅛" thickness. I recommend using a mandoline slicer if you have one available.
- In a saucepan over medium heat, add butter. Once melted, add onions and cook until they begin to brown and turn translucent, about 4-5 minutes. Add garlic and cook an additional 30 seconds. Add flour and stir to coat and create a paste. Cook for one minute.
- Whisk in broth and milk. Continue whisking until no lumps remain. Cook sauce for another 3-4 minutes, or until thickened slightly. Remove from heat. Add salt, pepper, and thyme, stirring to incorporate.
- In prepared 9x13 pan, arrange ¼ of sliced potatoes in the bottom of the dish, overlapping slightly. Pour ¼ of sauce over potatoes. Repeat once more, adding another layer of potatoes and sauce. Next, add half of shredded gruyere cheese in an even layer. Add two more layers of potatoes and sauce (for a total of four layers each of potato and sauce), and top with remaining shredded cheese.
- Cover casserole with foil and bake for 45 minutes. Uncover and bake an additional 15-20 minutes, or until potatoes can easily be pierced through with a fork in the center of the casserole. The thicker your potatoes are sliced, the longer it will take for them to cook through.
- Optionally, turn on broiler for 2-3 minutes to lightly brown cheese on top before serving.
- I recommend freshly shredding cheese from a block instead of using pre-shredded bagged cheese, which is often coated in an anti-clumping powder that becomes grainy when melted.
- Leftover casserole will keep for up to 4 days in a sealed container in the refrigerator.
- Casserole can be assembled ahead and stored in the refrigerator overnight before baking. Cover potatoes with plastic wrap, pressing down to keep out as much air as possible. Exposed potatoes may discolor slightly overnight. While oven is preheating, bring casserole to room temperature on the counter top, then bake as directed above.
- Casserole can be baked, cooled, and stored in the refrigerator overnight. To reheat entire baked casserole, bake, covered, at 350 degrees for 30 minutes, or until heated through in the middle.