A pretty and delicious potato side dish, this potato gratin uses thinly sliced potatoes stood on their sides in a pretty spiral pattern, then baked until tender in a creamy Gruyère, cheddar and Parmesan cheese sauce. The milk-based sauce is perfectly creamy and never curdled or grainy. Comfort food at its best, and sure to elevate any meal.
Creamy potatoes are always a treat, and this potato gratin is a little bit special, with potatoes set into the baking dish on their sides rather than layered flat. It makes for a pretty dish that has extra golden, crispy bits on top. The combination of Gruyère cheese with old white cheddar and Parmesan cheese ensures full-on cheese flavour.
Ingredients and substitutions
A few notes about the key ingredients …
Potatoes – This potato gratin starts with yellow-fleshed potatoes, such as Yukon Gold. They tend to hold their shape better than softer Russet potatoes.
Gruyère cheese – Nutty Gruyère cheese is the perfect complement for potatoes, in my opinion. It’s pricey, but worth it. The best substitute cheese options would be Swiss or Emmental.
Old white cheddar cheese – White cheddar is recommended mostly for appearance’s sake. You can certainly use orange old cheddar if that’s what is on hand.
Parmesan cheese – Freshly shredded Parmesan (from a block) is recommended.
Milk – As this dish relies only on milk for the sauce, use whole milk, if possible. This would be 3-3.5% butterfat milk. 2% will work, though it would be slightly less creamy, of course. I wouldn’t suggest any lower butterfat milk for this dish.
Chicken broth – Vegetable broth can be substituted for a vegetarian option.
How to make potato gratin: step-by-step
This is a visual summary of the steps to make this recipe. Scroll down to the Recipe Card below for the complete list of ingredients and instructions.
Step 1: Dry-fit your potatoes in your baking dish. They should fit with just a bit of space between.
Step 2: Thinly slice the potatoes.
Step 3: Arrange the sliced potatoes on their sides in the baking dish.
Step 4: Tuck the sliced onion between the potato slices.
Step 5: Prepare the cream sauce in a saucepan.
Step 6: Be sure to season the sauce well with salt and pepper!
Step 7: Add 3/4 of the shredded cheese to the sauce.
Step 8: Pour the cheese sauce over the sliced potatoes. Cover with foil and bake for 45 minutes.
Step 9: Remove the foil, top with the remaining shredded cheese, and return to the oven uncovered for 30-35 minutes to finish baking.
Pan size options for this potato gratin
I’ve used a shallow (2″ deep) oval ceramic au gratin baking dish that is 9 1/2 x 6 inches. Be sure to use a dish that isn’t too big. (See the step-by-step photos above. The 4 potatoes should just nicely fit in the pan with just a bit of room between them.)
If you don’t have a small au gratin dish, a 9-inch round baking dish is your best option. In a pinch, a deep-ish ceramic pie plate would work.
If you need more potatoes, double the recipe ingredients and fill a larger pan.
Making ahead, storing and freezing
These potatoes are best enjoyed freshly baked. If you need to make them ahead, it is best to fully bake the potatoes, cool them, then cover and refrigerate. Remove from the fridge and let stand at room temperature for 20-30 minutes, then reheat in a 350F oven loosely covered with foil for 20-30 minutes, removing the foil for the last few minutes to re-crisp the top slightly.
Store leftover cooked potatoes covered in the refrigerator for 3-4 days.
Freezing isn’t recommended, as the texture of the cream sauce may become grainy from the freeze/thaw process.
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Get the Recipe: Potato Gratin
Ingredients
- 4-6 Yukon Gold (yellow-fleshed) potatoes, unpeeled, thinly sliced
- 1 small onion, peeled, halved and thinly sliced
- 1 cup Gruyère cheese, shredded
- 1 cup old white cheddar cheese, shredded
- 1/2 cup Parmesan cheese, freshly shredded recommended
- 4 Tablespoons butter
- 4 Tablespoons all-purpose flour
- 2 cups milk, 2 or 3% recommended
- 1 cup chicken or vegetable broth
- 1 teaspoon garlic powder, not garlic salt
- 1 teaspoon kosher salt
- 1/2 teaspoon black pepper
Instructions
- Preheat the oven to 375F (regular bake setting – adjust as needed for convection/fan-assisted).
- Spray a 9-inch round shallow casserole dish or 9 1/2 x 6-inch oval au gratin baking dish with cooking spray and set aside. (A deep-dish pie plate will also work in a pinch.)
- Thinly slice the 4-6 Yukon Gold (yellow-fleshed) potatoes (unpeeled, thinly sliced) as thinly as you can cut them with a sharp knife. Peel the 1 small onion (peeled, halved and thinly sliced) and trim off the top and bottom slightly. Cut the onion in half from top to bottom, then cut into thin slices, cutting from the short side. Set aside.
- Prepare 1 cup Gruyère cheese (shredded), 1 cup old white cheddar cheese (shredded) and 1/2 cup Parmesan cheese (freshly shredded recommended)and set aside.
- In a large saucepan, heat the 4 Tablespoons butter over medium heat. Stir in the 4 Tablespoons all-purpose flour and cook, stirring, for about 1 minute. Slowly add the 2 cups milk (2 or 3% recommended), stirring constantly, then add the 1 cup chicken or vegetable broth. Cook, stirring, until the sauce is smooth and begins to thicken. Stir in the 1 teaspoon garlic powder (not garlic salt), 1 teaspoon kosher salt and 1/2 teaspoon black pepper.
- Remove the saucepan from the heat and add about 3/4 of the shredded Gruyère cheese, 3/4 of the shredded white cheddar cheese and 3/4 of the Parmesan to the sauce. Stir in briefly, then let stand for 1-2 minutes and stir again until the sauce is smooth.
- Arrange the potato slices in the prepared baking dish, standing them on their sides in the dish. Insert onion slices between the potato slices. Slowly pour the cheese sauce over the potatoes and onions, using a fork to gently separate the potato slices to allow the sauce to seep a bit between the potato slices. The cheese sauce should not completely cover the potato slices, leaving the tops slightly uncovered. You may not need to use all of the sauce, depending on your dish size or the size of your potatoes. (Refrigerate any leftover sauce to use for drizzling on cooked vegetables!) Season the casserole with a pinch more salt and some freshly ground pepper.
- Cover the baking dish tightly with foil and bake covered for 45 minutes.
- Remove from the oven and remove the foil. Top with the remaining shredded cheese. Return to the oven uncovered and bake for an additional 30-35 minutes, or until the potatoes are tender and the top is golden brown and bubbling.
- Allow to stand for about 10 minutes before serving.
- Store leftovers covered in the refrigerator for 3-4 days. Freezing isn't recommended, as the creamy sauce may become grainy after freezing and thawing. To reheat, remove from the refrigerator for 30 minutes, then heat in a a 350F oven loosely covered with foil until warmed through, about 15-20 minutes, removing the foil for the last few minutes to re-crisp the top a bit.
Notes
More potato recipes to love!
Hi! I’m Jennifer, a home cook schooled by trial and error and almost 40 years of getting dinner on the table! I love to share my favourite recipes, both old and new, together with lots of tips and tricks to hopefully help make your home cooking enjoyable, stress-free, rewarding and of course, delicious!
How many pounds would that be, one lb.?
Hi Elizabeth, it would probably be in the 1 1/4 – 1 1/2 lb range. Since Yukons come in a range of sizes, the best approach is to dry-fit in the pan as shown in the post. Sometimes it will be four potatoes, but it could be up to 6 if they are smaller.
I have always wanted to make this with a tenderloin roast for Holiday dinners. Recipes always make a point of best same day. I note you mention if must do in advance to complete the dish and then reheat. Is stopping at the midway point and finishing the cheese step next day a bad idea? I am thinking the potatoes could turn brown even though partially cooked? Not sure what other obvious down sides to this idea but any insight from you would be appreciated and followed. Thank you for all of your perfectly instructed recipes. Love your site, can always count on it.
Hi Den, I think the potential concern for par-baking these potatoes would be whether they are baked enough to stop the potatoes from browning in the refrigerator. It’s generally recommended to par-bake at least 75-80% cooked, and for this one, they would only be 60% cooked. I’d also be a little worried about how it might affect the texture of the potatoes to stop cooking earlier and then sit in the sauce in the fridge. I can tell you that I have fully baked and reheated these potatoes many times and I’ve never been disappointed. To me, it’s just a minor quality compromise for the ease of making them ahead :)