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If you’ve ever wished for a comfort food that wraps you in warmth and satisfies every craving, this Potatoes Au Gratin Recipe is exactly what you need. Layered with tender red potatoes, thinly sliced onions, and bathed in a luscious, cheesy sauce that melds sharp cheddar and nutty gruyere, it’s the kind of dish that transforms simple ingredients into pure magic. Rich, creamy, and beautifully golden on top, making this classic side is a delightful culinary journey that will have your family and friends asking for seconds—or even thirds!

Red potatoes whole and thinly sliced into translucent discs, arranged in neat small stacks; a medium onion thinly sliced into delicate rings fanned out beside the potatoes; three tablespoons of golden butter in a small vintage glass bowl; a wooden spoon resting next to a small heap of pale all-purpose flour; a tiny ceramic bowl with bright yellow dry mustard powder; a glass measuring cup filled with creamy white milk; a small rustic bowl of shredded sharp orange cheddar cheese; another bowl containing pale ivory shredded gruyere cheese; salt crystals and black peppercorns lightly scattered around on a clean white marble surface; soft natural light highlighting the varied textures—the smooth potato skins, the layered onions, creamy dairy, and powdery spices; subtle shadows creating depth; minimal props to keep focus on the vibrant colors and fresh ingredients; overhead shot, top down view, flat lay photography, professional food styling --ar 1:1 --q 2 --s 750 --v 6.1

Ingredients You’ll Need

What makes this Potatoes Au Gratin Recipe stand out is how these straightforward ingredients come together to create a harmonious blend of textures and flavors. Each item plays its part, from the tender red potatoes to the flavorful cheeses and the delicate hint of dry mustard that adds a subtle zing to the creamy sauce.

2½ pounds red potatoes: Their waxy texture holds up beautifully when sliced thin, giving you tender layers that don’t fall apart.
1 medium onion (thinly sliced): Adds sweetness and a gentle bite to balance the richness of the cheese.
3 tablespoons butter: Essential for building your creamy roux sauce, adding richness and depth.
3 tablespoons all-purpose flour: Thickens the sauce perfectly, ensuring it’s smooth and velvety.
1 teaspoon dry mustard powder: A secret little boost that lifts the cheese sauce with bright, tangy notes.
2 cups milk: The base of the sauce, bringing creaminess without overwhelming heaviness.
1 cup shredded cheddar cheese: Sharp and flavorful, it’s a classic choice that melts into luscious goodness.
½ cup shredded gruyere cheese: Adds a nutty, slightly sweet touch that elevates the overall flavor.
¾ teaspoon salt (divided): Balances all the flavors perfectly when sprinkled judiciously.
½ teaspoon black pepper (divided): Adds a mild heat and depth that enhances the dish’s complexity.

How to Make Potatoes Au Gratin Recipe

Step 1: Preparing the Oven and Ingredients

First things first, preheat your oven to 400°F. Washing your potatoes thoroughly and slicing them into paper-thin ⅛ inch slices is key since these delicate layers are the foundation for a tender, melt-in-your-mouth texture. Don’t forget to slice your onion as thinly as possible to ensure it softens perfectly during baking.

Step 2: Season and Layer Your Potatoes and Onions

Seasoning is crucial here—toss your thinly sliced potatoes and onions with half the salt and pepper. This step guarantees that every bite is flavorful inside and out. Then, stack the potatoes and onions in little piles and arrange these stacks on their sides in a greased casserole dish. This technique helps the cheese sauce seep right between the layers, soaking in all that lovely flavor.

Step 3: Crafting the Cheese Sauce

Next, melt butter in a saucepan and whisk in the flour, cooking for a few minutes to create a roux—this cooks out the raw flour taste so your sauce is silky and smooth. Add the dry mustard, remaining salt and pepper, then slowly whisk in the milk, heating until bubbly and thickened. Finally, stir in both your cheddar and gruyere cheeses until melted and luscious. This sauce is what takes the recipe from simple potatoes to a decadent dish that’s anything but ordinary.

Step 4: Assemble and Bake Your Potatoes Au Gratin Recipe

Pour this glorious cheese sauce over your potato and onion stacks, gently using a fork or spatula to separate and lift the stacks so the sauce can slip between every layer. Cover the dish tightly with foil that’s been sprayed with cooking spray to prevent sticking. Bake for one hour to allow the potatoes to cook through and the flavors to meld beautifully.

Step 5: Finishing Touches with a Golden Crust

Remove the foil carefully and return your dish to the oven for an additional 20 to 30 minutes, or until the top is lightly browned and irresistibly golden. This step is crucial for that crispy, bubbly crust that makes Potatoes Au Gratin Recipe so iconic. After baking, let the dish cool for about 15 minutes—it helps the sauce thicken slightly so it holds together perfectly when you serve.

How to Serve Potatoes Au Gratin Recipe

Garnishes

A sprinkle of freshly chopped parsley or chives adds not only a pop of vibrant green but also a fresh flavor contrast to the rich, cheesy layers. If you’re feeling indulgent, a few crispy breadcrumbs toasted with butter on top add amazing texture. These little garnishes bring your Potatoes Au Gratin Recipe to life, making it look as good as it tastes.

Side Dishes

This dish is a star side perfect for pairing with roasted meats like chicken, beef, or pork. The creamy potatoes amplify any protein beautifully, while a crisp green salad or steamed vegetables add a refreshing crunch to your meal to balance the richness.

Creative Ways to Present

Make your Potatoes Au Gratin Recipe feel like a special occasion by serving it in individual ramekins or mini cast iron skillets for a rustic, charming look. For buffet or potluck settings, try spooning it into hollowed-out bell peppers or mushrooms for a unique presentation that’s sure to impress your guests.

Make Ahead and Storage

Storing Leftovers

Leftover Potatoes Au Gratin Recipe keeps wonderfully in the fridge. Store it in an airtight container for up to 3 days, and it will maintain its creamy texture and bold flavors. Just be sure to cool the dish thoroughly before refrigerating to keep everything fresh and safe.

Freezing

Freezing this dish is doable, but because of its creamy texture, it’s best to freeze before baking. Assemble the potatoes and sauce in a freezer-safe dish, cover tightly, and freeze for up to 2 months. When you’re ready, thaw overnight in the fridge and bake as directed, adding a bit of extra time if needed. Avoid freezing leftovers after baking to preserve quality.

Reheating

To reheat, cover your leftovers with foil and warm in a 350°F oven until heated through, which usually takes about 20-30 minutes depending on portion size. This helps retain the creamy consistency without drying the top. If you’re in a hurry, the microwave works too—just cover loosely to avoid splatters and heat in short bursts to keep things nice and creamy.

FAQs

Can I use other types of potatoes for this recipe?

Absolutely! While red potatoes hold their shape beautifully, Yukon Gold or even Russet potatoes can work. Just remember that Russets are starchier and may break down more during baking, resulting in a creamier texture.

What can I substitute for Gruyere cheese?

If you can’t find Gruyere, a good-quality Swiss cheese or even fontina makes an excellent substitute. They both melt well and offer a mild nuttiness that complements the cheddar nicely.

Can Potatoes Au Gratin Recipe be made dairy-free?

Yes! Use a plant-based butter and a non-dairy milk like oat or almond milk. For cheese, vegan cheese shreds work in this recipe, though the flavor and texture will be slightly different but still delicious.

Is it possible to make this recipe gluten-free?

Certainly. Substitute the all-purpose flour with a gluten-free flour blend or cornstarch (use slightly less cornstarch, about 2 tablespoons) to thicken the sauce. Make sure all other ingredients, especially cheeses, are gluten-free.

How do I get the cheese sauce thick enough?

Patience and heat control are key. Cook your butter and flour mixture long enough before adding the milk, then whisk constantly as it thickens. The sauce should be smooth, creamy, and coat the back of a spoon before adding the cheese.

Final Thoughts

I can’t recommend this Potatoes Au Gratin Recipe enough for anyone craving a cozy, cheesy, indulgent dish that’s surprisingly simple to make. It’s a timeless classic that always impresses, whether for holiday dinners or a weeknight treat. Once you try it, I’m willing to bet it becomes one of your go-to comfort foods too—so roll up your sleeves, gather your ingredients, and get ready to scoop up creamy, golden layers of happiness!