Creamy Au Gratin Potatoes

Cheesy, creamy, and buttery, this is the potato side you've been looking for. Great with just about any protein—chicken, ham, turkey, or even a steak—this versatile side does require quite a bit of slicing, but it's worth it for layers of ooey-gooey goodness. Plus, it's a great excuse to break out the mandoline collecting dust in the cupboard. Just don't forget to use the hand guard.

If you've ever had scalloped potatoes, au gratin is like that dish's French cousin, with lots of cheese folded in. (Truth be told, the names are often used interchangeably.) Whatever you call it, this dish will become your go-to side dish for everything from holiday buffets to weeknight suppers.

Ingredients for Creamy Au Gratin Potatoes

The ingredient list for this recipe is fairly short and simple, but there are a few key ingredients that make this creamy potato side as delicious as it is.

Yukon gold potatoes
Our Test Kitchen recommends using Yukon gold or gold potatoes for this au gratin. Test kitchen coordinator Amanda Stanfield says, "They work well because you eliminate having to peel them, and the starch content holds up well during the baking process and doesn't get as mushy as russet potatoes would."

White Cheddar cheese
You might be wondering what makes this cheese any different from regular Cheddar. The difference is slight and superficial, as white Cheddar is simply Cheddar cheese that has not been dyed orange with a natural vegetable dye called annatto. The orange tint is part of the Cheddar making tradition in England, as Cheddar was once made with milk from cows with a diet that produced an orange tint to their milk.

There is no difference in taste or texture between white Cheddar and orange Cheddar, but like orange Cheddar it comes in mild, medium, and sharp varieties. For this recipe we suggest a mild version and use white instead of orange because of how it blends seamlessly into the cream sauce.

Fresh thyme
With its subtle lemon flavor, fresh thyme adds a bit of brightness to this rich and creamy dish. It is commonly paired with potatoes, but also pairs well with most proteins, like chicken, fish, or pork.

To easily remove the leaves from the stems, simply pinch the top of the sprig and slide your fingers down it to release the leaves. You can use dried thyme if you can't find it fresh, but use about half the amount, as dried thyme is much more potent. Other hearty fresh herbs like rosemary can be used in place of thyme, too.

How to Make Creamy Au Gratin Potatoes

Just 30 minutes of hands-on cooking is needed to make this decadent potato side.

Step 1. Make the sauce

Preheat the oven to 325°F, and grease an 11- x 7- inch baking dish with butter.

Melt the remaining butter in a medium saucepan over medium-high. Add garlic and thyme, and cook, stirring constantly, until fragrant.

Mix in the cream, and season with salt. Reduce heat to low, and cook for another 5 minutes.

Meanwhile, whisk together warm water and cornstarch in a small bowl. Stir the cornstarch mixture into the saucepan, and cook, whisking constantly, until thickened slightly.

Whisk in Parmesan cheese and 1/2 cup of the Cheddar; cook, whisking often, until smooth and thickened, and then remove the sauce from the heat.

Step 2. Assemble

Gently toss together potato slices, black pepper, and remaining salt in a medium bowl. Arrange slices in an even layer on the bottom of the baking dish. Repeat, creating layers with the remaining potatoes.

Pour the sauce evenly over the potatoes and sprinkle with the remaining Cheddar. Bake until the potatoes are tender, and the top is golden brown, 50 minutes to 1 hour. Remove from the oven, and let stand for 15 minutes. Garnish with additional fresh thyme leaves.

Slicing Potatoes for Creamy Au Gratin Potatoes

Cutting potatoes 1/8-inch thick can be a little tricky, but it's important to get your potatoes that thin so that they cook properly. Here a few tips:

1. Grab a sharp knife.

Cutting potatoes this thin with a dull knife is a recipe for disaster. Make sure your knife is super sharp before you start, and make sure to tuck your finger tips in while slicing.

Once you get down to the end of the potato, don't be hero–it's better to discard that nub than cut yourself trying to slice it precariously.

2. Better yet, grab a mandoline.

As scary as they may seem, mandolines get clean, even, and most importantly very thin slices out of a potato. Once you know what you're doing, the mandoline is faster than slicing by hand, and unless you have rockstar knife skills, they will probably be more consistent slices, too.

The key is using a hand guard or glove to protect your fingers, and apply even pressure. Just like slicing by hand, discard the end of the potato when it gets too small to avoid any injuries.

3. Keep a bowl of ice water nearby.

Dropping the potato slices into a bowl of ice water while you prep will prevent the slices from oxidizing and turning brown. Strain and pat dry when ready to assemble the gratin.

Frequently Asked Questions

Making potatoes au gratin and having a few issues? We can help.

Why are my au gratin potatoes watery?

If you stored the sliced potatoes in water to prevent discoloring, but didn't drain them well and pat them dry before adding them to the baking dish, you may have added extra water to the dish. You could have also used the wrong kind of potato, as some waxy potatoes can release more water than starchier potatoes. Stick with Yukon Gold for the perfect consistency.

Why won't my potatoes get soft?

This might have to do with how the potatoes were sliced. If they weren't sliced nice and thin, or were inconsistently cut, it will take longer for the potatoes to cook. Or if way too thick, they may not cook through by the time the top is brown and set. If the tip of a knife inserted into the center of the casserole meets resistance, cover the casserole with foil and keep cooking until they are soft.

Can au gratin potatoes be made ahead?

Yes! You can make the sauce and assemble the casserole, cover, and leave it in the refrigerator for up to two days before baking. Bake straight from the fridge according to the recipe, although it might take a few more minutes to bake from cold.

What do you serve with au gratin potatoes?

These potatoes go great with just about any protein, from a roast chicken to pork chops. They make a great addition to the holiday table, but are just as good alongside a steak on a weeknight.

Editorial Contributions by Alana Al-Hatlani.