Cheesy Au Gratin Potatoes (The Best Thanksgiving Potatoes EVER!)

When it comes to comforting, crowd-pleasing side dishes, there are few that truly hit the mark like a well-made au gratin potato. This recipe, honed over years of family gatherings and holiday feasts, consistently earns rave reviews and is a staple on our table, especially during Thanksgiving. It’s a dish that brings warmth and richness to any meal.

Why This Cheesy Au Gratin Potatoes (The Best Thanksgiving Potatoes EVER!) Works

This au gratin recipe succeeds because it balances creamy, cheesy goodness with the subtle earthiness of potatoes. The layers cook evenly, ensuring tender potatoes throughout, while the topping achieves a beautiful golden-brown crispness. It’s approachable for home cooks of all levels and always feels special enough for a holiday.

Ingredients

• 2 ½ pounds Yukon Gold potatoes, thinly sliced (about 1/8-inch thick)
• 1 teaspoon salt, plus more to taste
• ½ teaspoon black pepper, plus more to taste
• 2 tablespoons unsalted butter
• 1 medium yellow onion, thinly sliced
• 2 cloves garlic, minced
• 2 tablespoons all-purpose flour
• 2 cups whole milk
• 1 cup heavy cream
• 1 ½ cups shredded Gruyère cheese (about 6 ounces)
• 1 cup shredded sharp cheddar cheese (about 4 ounces)
• Pinch of nutmeg (optional, but recommended)

With these foundational elements in place, we can begin the process of transforming simple ingredients into a dish that’s both elegant and deeply satisfying. The quality of your potatoes and cheeses will make a noticeable difference, so choose wisely!

How to Make It

1. Preheat your oven to 375°F (190°C). Butter a 9×13 inch baking dish generously.
2. Prepare the potatoes: Peel the potatoes if desired, or scrub them well if leaving the skin on. Slice them thinly and uniformly, about 1/8-inch thick. A mandoline slicer is very helpful here for consistency, but a sharp knife and steady hand will also work. As you slice the potatoes, place them in a large bowl. Season them with 1 teaspoon of salt and ½ teaspoon of black pepper. Toss gently to distribute the seasoning evenly. The salt will draw out some moisture and begin to tenderize the potatoes, contributing to a better texture.
3. Sauté the aromatics: In a medium saucepan, melt the 2 tablespoons of butter over medium heat. Add the thinly sliced yellow onion and cook, stirring occasionally, until softened and translucent, about 5-7 minutes. You’re not looking to brown the onions aggressively here, just to soften them and release their sweetness. Add the minced garlic and cook for another minute until fragrant, being careful not to burn it.
4. Make the roux: Sprinkle the 2 tablespoons of all-purpose flour over the softened onions and garlic. Stir and cook for about 1-2 minutes, until the flour is lightly toasted. This is the base of your sauce, and toasting the flour slightly helps to cook out the raw flour taste and thicken the sauce more effectively.
5. Create the creamy sauce: Gradually whisk in the 2 cups of whole milk, a little at a time, ensuring that each addition is incorporated smoothly before adding more. Once all the milk is incorporated, whisk in the 1 cup of heavy cream. Bring the mixture to a gentle simmer, stirring constantly. Continue to simmer and stir for about 3-5 minutes, until the sauce has thickened enough to coat the back of a spoon. This is a crucial step for achieving a luscious, creamy consistency for your au gratin.
6. Add the cheeses: Remove the saucepan from the heat. Stir in 1 cup of the shredded Gruyère cheese and ½ cup of the shredded sharp cheddar cheese. Stir until the cheeses are melted and the sauce is smooth and creamy. If using, stir in a pinch of nutmeg. Taste the sauce and adjust seasoning with additional salt and pepper as needed. Remember that the potatoes and cheese will add more salt, so don’t over-salt at this stage.
7. Assemble the dish: Arrange about half of the seasoned potato slices in an even layer in the prepared baking dish. Pour about half of the cheese sauce evenly over the potatoes. Add the remaining potato slices in another even layer. Pour the rest of the cheese sauce over the top, ensuring all the potatoes are well-coated. Gently press down on the potatoes with a spatula to submerge them slightly in the sauce; this encourages even cooking and prevents the top layer from drying out too quickly.
8. Bake: Cover the baking dish tightly with aluminum foil. Bake in the preheated oven for 45 minutes.
9. Brown the topping: Remove the foil and sprinkle the remaining ½ cup of Gruyère cheese and ½ cup of sharp cheddar cheese evenly over the top of the potatoes. Return the dish to the oven, uncovered, and bake for another 20-25 minutes, or until the potatoes are tender when pierced with a fork and the cheese topping is golden brown and bubbly. The aroma that fills your kitchen at this stage is truly enticing.
10. Rest: Let the au gratin potatoes rest for at least 10-15 minutes before serving. This allows the sauce to set slightly, making it easier to serve and preventing it from being too runny.

This step-by-step process guides you through creating a comforting and flavorful cheesy au gratin potato dish that will be a highlight of any meal, particularly holiday celebrations. The key lies in consistent preparation and allowing each stage to contribute to the final delicious outcome.

Here’s another great option:  Slow Cooker Beef and Potatoes au Gratin

• Calories: Approximately 450-550 per serving (depending on exact ingredient amounts and serving size)
• Protein: Around 15-20g
• Fat: Roughly 30-40g (this is a rich dish!)
• Carbohydrates: Approximately 30-40g
• Fiber: Around 3-5g
• Sugar: About 5-8g (mostly naturally occurring from potatoes and milk)
• Sodium: Varies widely based on cheese and added salt, but generally in the 500-800mg range

It’s important to remember that these are approximate values. The exact nutritional content can fluctuate based on the specific brands of ingredients used, the precise quantities measured, and the final portion size. For a truly accurate breakdown, using a nutrition calculator with your precise ingredient list would be recommended. However, this gives a good general idea of what you’re consuming with this indulgent dish. While it’s certainly not a “light” meal, it’s a fantastic source of energy and satisfaction. The protein and fat content contribute to its filling nature, making it a satisfying side that can even stand on its own for a hearty meal when paired with a salad or protein.

How to Serve It

• As a rich side dish for Thanksgiving dinner, alongside turkey, stuffing, and cranberry sauce.
• A comforting accompaniment to roasted meats like prime rib, pork loin, or roasted chicken.
• Paired with a crisp green salad and a light vinaigrette to balance the richness of the potatoes.
• A hearty vegetarian main course when served with a side of steamed green beans or a fresh tomato salad.

Serving this au gratin promptly after it has rested ensures the optimal texture and temperature, allowing your guests to experience its full glory. The versatility of this dish means it can elevate many different types of meals, from casual weeknight dinners to the most festive holiday spreads.

Common Mistakes

• Slice thickness inconsistency: If potatoes are sliced too thick, they may not cook through evenly, leading to some tender pieces and some still-firm chunks. Conversely, if too thin, they can become mushy and lose their distinct potato texture. Aiming for a uniform 1/8-inch thickness is key. Using a mandoline slicer can greatly help in achieving this evenness.
• Not pre-salting the potatoes: Skipping the initial salting of the sliced potatoes can result in a dish that tastes bland. The salt penetrates the potato as it sits, enhancing its flavor from the inside out. It also helps to draw out a little moisture, which can improve the final texture by preventing a watery sauce.
• Over-boiling the sauce: While you want the sauce to thicken, boiling it too vigorously or for too long can cause it to break or become grainy, especially if dairy is involved. Gentle simmering is usually sufficient for thickening and melding the flavors.
• Under-seasoning: Potatoes are bland on their own and need adequate salt and pepper, both in the potato mixture and in the sauce. Taste the sauce before assembling and adjust as needed, keeping in mind that cheese also adds saltiness.
• Not letting it rest: While it’s tempting to dig in immediately, allowing the au gratin to rest for at least 10-15 minutes after baking is crucial. This period lets the sauce thicken further and the flavors to meld, preventing a soupy consistency when served and making it much easier to portion neatly.

Avoiding these common pitfalls will significantly increase your chances of producing a truly delicious batch of au gratin potatoes every single time. Attention to detail, especially in slicing, seasoning, and resting, makes a substantial difference in the final outcome.

Storage and Reheating

• Storage: Once completely cooled, transfer any leftover au gratin potatoes to an airtight container or cover the baking dish tightly with plastic wrap and then aluminum foil. Store in the refrigerator for up to 3-4 days. Ensure it’s properly sealed to prevent it from absorbing odors from other foods in the fridge and to maintain moisture.
• Reheating: For the best results, reheat in a moderate oven, around 350°F (175°C). Cover the dish with foil to prevent the top from drying out and bake until heated through, about 20-30 minutes. For a crispier top, remove the foil for the last 5-10 minutes of reheating. Alternatively, you can reheat individual portions in the microwave, but the texture may not be as pleasing as oven reheating. Sometimes, a few extra pats of butter or a splash of milk added before reheating can help revive the creaminess.

Proper storage and reheating are key to enjoying these delicious potatoes even days after the initial meal. Patience during reheating will reward you with a dish that’s nearly as good as it was fresh out of the oven. Don’t be discouraged if the texture changes slightly; it’s still a wonderful way to enjoy leftovers.

Leftover Ideas

• Potato Patties: Mash or finely chop the leftover au gratin potatoes, mix with a binder like an egg and a little flour or breadcrumbs, and pan-fry them into crispy potato patties. These are excellent as a side or even as a base for a fried egg breakfast.
• Shepherd’s Pie Topping: Use the leftover au gratin potatoes as a rich and flavorful topping for a classic Shepherd’s Pie. Simply spread them over your favorite ground meat filling before baking.
• Gratin-Stuffed Peppers/Mushrooms: Mix some of the leftover potatoes with a little extra cheese and seasonings. Use this mixture to stuff bell peppers or large mushroom caps before baking until tender and golden.
• Savory Bread Pudding/Casserole: Layer the leftover potatoes with cubes of stale bread, some sautéed vegetables (like spinach or mushrooms), and pour a mixture of eggs and milk over the top. Bake until set and golden for a hearty breakfast or brunch casserole.
• Added to a Frittata or Quiche: Chop up the potatoes and fold them into a frittata or quiche mixture for an added layer of flavor and creamy texture.

Leftovers can offer a fantastic opportunity to get creative in the kitchen, transforming a beloved side dish into entirely new and exciting meals. These ideas are just starting points to inspire your own culinary adventures with this versatile dish.

Print