A Family Tradition Worth Sharing: Perfect Au Gratin Potatoes
Growing up, potatoes au gratin was the special occasion potato at our house. Mom always made them for holidays, so spotting that cozy casserole dish bubbling away on the table meant we were in for a treat!
To me, au gratin potatoes will forever taste like celebration and Mom’s kitchen. 🥰
A lifetime’s worth of experience loving these fancy French potatoes comes with strong opinions about what makes a perfect gratin. The version I love most is simple and classic: thinly sliced potatoes and sweet onion baked in a cheesy cream sauce until they’re deeply browned across the top and completely tender throughout.
That’s exactly the version I had in mind when I set out to develop an au gratin potatoes recipe for PWWB – nothing over-the-top or reinvented, just a classic done really, really well.
Alternate Gratins
This classic recipe will always have my heart, but sometimes it’s fun to shake things up! As an au gratin potatoes family, there is a different version we make often:
- Mom’s maximalist Loaded Au Gratin Potatoes are over-the-top in all the best ways, with an extra-smoky, bacon-infused Gouda cheese sauce and piled with classic loaded baked potato toppings – crispy bacon, sour cream, chives, and more.
The 2 Test Kitchen Secrets for Classic Au Gratin Potatoes
Funny enough, for as much as I love them, au gratin potatoes have always been my culinary Achilles’ heel. No matter how thinly I sliced everything or how long I baked it, something was always off: the onions held onto some crunch, the sauce tasted one-note or split in the oven – sometimes all at once! 🫠
Through a lot of recipe testing, 2 key breakthroughs ended up making all the difference:
Secret #1: Swap onions for leeks! This light bulb moment came while developing my French-Style Creamy Braised Leeks and seeing just how tender they became when gently cooked in cream: why not use leeks in au gratin potatoes too?! 💡 Sure enough, thinly sliced leeks give the same sweet-savory allium flavor I love so much in my family’s version, but they practically melt into the potatoes as they slowly bake. 🤩
Secret #2: Simple really is best. With mild-mannered potatoes and cream making up the bulk of the dish, I couldn’t resist trying to punch up the flavor with Dijon mustard and spices like garlic powder, onion powder, and paprika – but the extra seasoning ended up muddying the rich, savory flavor I was after. 😭 Instead, infusing heavy cream with a few simple aromatics was the ticket.
For the Best Au Gratin Potatoes, Start With Yukon Golds 🥔
As the star of the show, the type of potato you use makes all the difference. For me, it’s Yukon Golds all the way: their naturally buttery flavor is right at home with all the cream and cheese, and their texture is ideal for gratin too. Where starchy varieties like Russets are more prone to falling apart during a long bake, I find waxier gold potatoes hold their shape beautifully, creating the gorgeous, distinct layers that make a gratin feel so special.
Bonus: prep is a breeze – there’s no need to peel tender-skinned Yukon Golds! 🙌🏼
Essentials for Best-Ever Potatoes Au Gratin
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Many potato au gratin recipes start with mornay (a roux-based cheese sauce) for an especially thick and cheesy result. But for a classic gratin, I prefer something simpler: garlic and herb-infused cream. The aromatics give a little extra oomph without changing the cream’s texture – it slowly reduces as the gratin bakes, coming together with the potatoes’ natural starches and melty cheese to create a beautifully creamy sauce that isn’t too heavy.
Gently heat the heavy cream with smashed garlic and fresh thyme just until it begins to simmer and steam, then set aside to steep.
Why? ⇢ Gently warming the garlic and thyme in the cream helps coax out their flavor, much more so than simply tossing everything together. Just be sure to keep the heat low – a hard boil can cause the sauce to curdle or break!
Add the sliced potatoes and leeks to a bowl with shredded gruyère and grated Parmesan, and mix with the cream sauce.
Cheese makes the au gratin potatoes! My idea of a perfect classic gratin isn’t especially melty or ooey-gooey, so I tested a batch without any cheese to see how much it was really doing – turns out, a lot! 😅 The flavor fell totally flat and the sauce was so thin the potatoes practically slid out of the pan. The cheese isn’t there to make the potatoes cheesy, but to give the cream sauce tons of savory depth and enough body to bind everything together.
To avoid a grainy or greasy result, be sure to use a good-quality cheese suited for melting. Of all the varieties I tested, gruyère is my favorite: it melts beautifully and adds a rich, nutty flavor without overpowering the potatoes.
Since the potatoes are already coated with cream and cheese, there’s no need to meticulously layer everything – just transfer the mixture to a greased baking dish and press it out evenly.
Tip! ⇢ Delicate leeks burn easily! Be sure to tuck any exposed pieces beneath the potatoes so they don’t char during the long bake.
Bake the au gratin potatoes in two phases: first, cover the casserole tightly with foil for the initial bake; then remove the foil, sprinkle a fresh layer of grated Parmesan over top, and return it to the oven, uncovered, to finish.
There’s no rushing au gratin potatoes! I learned this lesson the hard way, batch after batch: my gratin would somehow end up raw through the middle and burnt on top all at once! 😵💫 Through lots of testing, I found that they need more time in the oven than you might think – and how that time is split matters just as much: baking the casserole covered traps in steam, helping the potatoes cook completely through in 1 hour; following that with 20-30 minutes of uncovered baking allows the cream to reduce just enough while the top gets golden. You get tender potatoes, perfectly thickened sauce, and a beautifully golden, bubbly top every time!
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Serving Suggestions
Au gratin potatoes are made for a holiday table. Mom always serves them alongside our family’s Tried and True Maple Glazed Ham for Easter dinner, and they’re the perfect decadent potato side dish for a Christmas roast like a showstopping Garlic and Herb Prime Rib or Foolproof Beef Tenderloin. Really, any occasion that calls for something extra-special!
But there’s also something so rustic and cozy about a bubbling casserole of creamy potatoes, and this recipe is easy enough to make just because. Pair it with roast chicken or steak for Sunday supper, and don’t be surprised if you start finding excuses to make au gratin potatoes all the time! 🥰
The Last Au Gratin Potatoes Recipe You’ll Ever Need
- Prep Time: 20 minutes
- Cook Time: 1 hour, 30 minutes
- Total Time: 1 hour, 50 minutes
- Yield: 10–12 servings 1x
- Category: Side Dishes, Thanksgiving Recipes, Christmas Recipes
- Method: Baking
- Cuisine: French
- Diet: Gluten-Free
Description
This is it: the last Au Gratin Potatoes recipe you’ll ever need!
Buttery Yukon Gold potatoes slowly bake in a thyme-infused cream sauce with thinly sliced leeks, melty Gruyère, and Parmesan cheese, then finish bubbly and golden on top.
Inspired by the special-occasion potatoes my mom made for every holiday meal throughout my childhood, I’ve tested this treasured family recipe until every bite is perfectly tender, creamy, and deeply savory. A foolproof potato casserole and side dish made for Christmas, Thanksgiving, and cozy Sunday suppers.
Ingredients
- 3 pounds Yukon Gold potatoes, sliced ⅛-inch thick
- 2 small leeks, cleaned and thinly sliced (about 1 heaping cup)
- 12 ounces good-melting cheese (I love Gruyère, smoked gouda, or comte), freshly shredded (about 3 cups)
- 1 ¼ cups finely grated Parmesan cheese, divided
- kosher salt and black pepper, to season
- very soft butter, for greasing the pan
for the thyme cream:
- 3 ½ cups heavy cream
- 10 cloves garlic, smashed and roughly chopped
- 3 tablespoons fresh thyme leaves
Instructions
METHOD OVERVIEW
Steep cream with garlic and thyme. Toss sliced potatoes, leeks, shredded cheese, about ⅓ of the Parmesan, salt, pepper, and the warm cream. Layer the mixture into a buttered casserole dish, finishing with a layer of potatoes (rather than leeks) and spooning any extra cream over top. Bake covered 60 minutes, then uncover, top with reserved Parmesan, and bake 20-30 minutes longer until golden brown and tender. Let cool slightly, then serve straight from the pan.
STEP-BY-STEP INSTRUCTIONS
- Prep the oven and pan: Preheat the oven to 400 degrees F, ensuring a rack is positioned in the center of the oven. Generously butter (or coat with nonstick cooking spray) the base and sides of a 9×13-inch pan (I use a 4-qt casserole dish) and set aside.
- Steep the thyme cream: In a small saucepan, combine the heavy cream, garlic, and thyme. Bring to a gentle simmer over medium heat and cook 4-5 minutes, just until fragrant. Remove from the heat and set aside to steep while you prepare the remaining ingredients.
- Meanwhile, prep the potatoes and leeks: Thinly slice the potatoes about ⅛-inch thick. A mandoline is helpful here for evenly thin slices, though a sharp knife works as well. Trim, clean, and thinly slice the leeks.
- Build the potato mixture: Add the sliced potatoes, leeks, shredded cheese, and ½ cup of the Parmesan to a large bowl. Season with a scant 1 teaspoon kosher salt and a few twists of black pepper. Pour the warm thyme cream over the mixture and toss well with your hands, separating any potato slices that are sticking together so the cream evenly coats everything.
- Assemble the gratin: Transfer the potato mixture to the prepared baking dish, arranging it in even layers. It’s best to finish with a layer of potatoes on top (rather than leeks). Spoon any extra cream from the bowl evenly over the assembled gratin. It’s okay if this gets a little messy – just wipe any drips from the pan before baking to prevent burning.
- Bake the au gratin potatoes: Cover the baking dish tightly with foil and transfer to the oven. Bake covered for 60 minutes. Remove the foil and sprinkle the remaining ¾ cup Parmesan over the top. Return to the oven and bake uncovered 20-30 minutes longer, until the top is golden brown and the potatoes are tender when pierced with a fork.
- Serve: Allow the au gratin potatoes to cool 10-15 minutes so the cream begins to set, then serve warm.
Notes
- Potatoes: Yukon Gold potatoes are my favorite for au gratin. Compared to starchier varieties like Russets, Yukon Golds have a naturally buttery flavor and creamy texture that becomes perfectly tender as they bake. Plus, their thin skins mean there’s no need to peel them. For best results, use a mandoline to slice the potatoes evenly to about ⅛-inch thick so they cook at the same rate.
- Storage and Reheating: Leftover au gratin potatoes will keep, stored in an airtight container in the refrigerator, for up to 4 days. Reheat in the microwave or in a 350 degree F oven or air fryer until warmed through. The air fryer is my favorite – it revives the golden edges beautifully while keeping the potatoes creamy and tender.
Nutrition
- Serving Size:
- Calories: 587
- Sugar: 4.5 g
- Sodium: 571.8 mg
- Fat: 44 g
- Saturated Fat: 27.4 g
- Trans Fat: 1 g
- Carbohydrates: 30.4 g
- Fiber: 3.4 g
- Protein: 19.6 g
- Cholesterol: 138.8 mg
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I love that these bring back such nice memories for you. I’ve never had very good luck with these kinds of potatoes but I’ll give this a try because it sounds like you finally nailed it! They look so pretty and appetizing.
Thanks, Chris! We hope you enjoy them!