These creamy Au Gratin Potatoes are made with a classic combination of cream, fresh garlic, Gruyere, Parmesan, thyme, and sliced russet potatoes. It’s an elegant and indulgent side dish recipe that’s easy to make and pairs well with just about everything!

Be sure to try my Green Bean Casserole, Sausage Stuffing, and Corn Casserole next!

Au Gratin Potatoes in a baking dish topped with chives, thyme, and a serving spoon on the side.

Au Gratin Potatoes

When it comes to potato recipes, Au Gratin Potatoes will always win for flavor and indulgence! This is the ultimate side dish that pairs so well with just about anything! It’s make-ahead friendly, and is sure to impress family and friends every time! Don’t miss my pro tips below!

Why You’ll Love This Recipe

Simple, flavorful, and indulgent: This recipe is simple, but SO flavorful. Traditionally, Au Gratin Potatoes are not made with flour and this recipe is no exception. The cream sauce thickens from the starch in the potatoes as they cook. The classic ingredients include butter, cream, garlic, fresh thyme, gruyere, and Parmesan cheese. 

For my own special twist: I like to caramelize diced onions at the beginning. This adds depth of flavor and a hint of sweetness that pairs so well with the Gruyere and fresh thyme! 

How to Make It

Note: This is an overview. See recipe card below this post for ingredient quantities and full instructions.

Caramelize onions in butter. Add garlic and fresh thyme. Add heavy cream and milk. Bring to a boil, then remove from heat. Gradually sprinkle in Gruyere and Parmesan cheese, then add salt and pepper.

A pot of diced onions and butter next to a pot of caramelized onions with cream sauce being added.

Slice peeled russet potatoes into thin, 1/8-inch slices. Layer 1/3 of them on the bottom of a lightly greased baking dish and add 1/3 of the cream sauce. Repeat two more times.

Sliced potatoes in a mandoline slicer container next to potato slices in a baking dish with sauce being added.

Cover and bake at 350° for 1 hour. Remove cover and bake for 30 minutes. Optional: Broil at 425°  for 1-2 minutes to brown the top more. Let sit for 5-10 minutes prior to serving Garnish with chives and serve!

A baking dish filled with Au Gratin Potatoes before and after being baked.

Make Ahead Method

  • Assemble as outlined and bake at 350° for 45 minutes. Let it cool completely, then cover and refrigerate for up to 2 days. (It will be very saucy and still on the thin side.)
  • When ready to serve: Let it sit out at room temperature for 1 hour. Bake covered at 350° for 20 minutes. Remove cover and bake for 30 more minutes, or until bubbly and hot. Broil for 1 minute at the end if desired.

Pro Tips

  • Potatoes: Use russets! They have a high starch content which thickens the sauce as they cook. They also absorb the sauce during cooking which is necessary- it makes them more flavorful and there is plenty of sauce to be absorbed. Yukon Golds are the next best option. Avoid waxy potatoes like red potatoes, they won’t absorb or thicken the sauce. 
  • Slice the potatoes thin: I’d almost call them paper thin (1/8th of an inch). This ensures they cook through all the way through. 
  • Use a Mandoline: This is the quickest and most accurate way to get thin, even slices. Use it with caution: Use every safety measure and safety tool provided and then some. They are very sharp and it’s easy to cut your fingers. (Trust me.)
  • Cheese: a 6 oz. block of Gruyere is enough to make 2 cups shredded. (I use 5.5 oz. of the block) I use Emmi Le Gruyère Cheese and Belgioioso Parmesan. Fontina Cheese makes a great addition to this as well. Cheddar can be used if needed, but I’d recommend Gruyere if at all possible.
  • Shred/Grate the cheese from a block. Don’t use packaged shredded/grated cheese as it won’t melt as well or taste as good.
  • Garlic– Definitely use fresh cloves for this recipe (vs. jarred).
  • Sauce: Keep two things in mind: 1.) It’s thin at first, but thickens more and more as the dish cooks. 2.) There is a lot of it, but the potatoes continue to absorb it during cooking, and some of it evaporates when it’s cooked without the cover. 

Storage

  • Store in an airtight container and refrigerate for up to 5 days. While leftovers can definitely be frozen, they don’t reheat exactly back to their original consistency.

Side view of Au Gratin Potatoes in a baking dish with a serving spoon on the side.

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Cheesy Au Gratin Potatoes in a cream sauce with chives on top and a serving spoon on the side.

Au Gratin Potatoes

Prep Time: 20 minutes
Cook Time: 2 hours
Total Time: 2 hours 20 minutes
5 from 2 ratings
Servings: 12 people
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These creamy Au Gratin Potatoes is an easy side dish recipe that's make-ahead friendly and pairs well with just about anything! Classic ingredients include cream, Gruyere, Parmesan, thyme, fresh garlic, and more!

Ingredients

US Customary - Metric
  • 1 small yellow onion, finely diced
  • 3 tablespoons salted butter
  • 4 cloves fresh garlic, minced
  • 2 teaspoons fresh thyme leaves
  • 2 cups heavy cream
  • ½ cup milk
  • 2 cups shredded gruyere cheese
  • ½ cup grated Parmesan cheese
  • ¼ teaspoon EACH: Salt, pepper
  • 2 ½ lbs. russet potatoes
  • Chives, to garnish

Equipment

Instructions

  • Preheat oven to 350°F. This can be done in step 4 after the onions are caramelized as well.
  • Combine the heavy cream and milk in a medium measuring cup with a spout. Temper in the microwave for 1 minute, then set aside.
  • Add the diced onions and butter to a soup pot over medium heat. Soften for 10 minutes, stirring often. Reduce heat to medium-low and cook for 10-15 more minutes, stirring frequently, until they begin to brown and caramelize slightly. Add the garlic and thyme and cook for 2 minutes.
  • Turn heat off and let the pot cool for 1 minute. Gradually stir in the heavy cream/milk. Set the heat to medium-high and bring the liquid to a boil, then remove from heat.
  • Gradually stir in the gruyere and Parmesan cheese, giving it a chance to melt as it's added a little at a time. Stir in the salt and pepper.
  • Cut the potatoes into 1/8-inch thick slices, no thicker or they won’t cook through. A mandoline slicer makes this much easier.
  • Arrange 1/3 of the potatoes on the bottom of a lightly greased baking dish. (Mine is 2.5 quarts. A 9 x 13-inch baking dish also works.) Pro Tip: Lightly sprinkle each layer of the potatoes with a little salt.
  • Add 1/3 of the sauce over the potatoes. Repeat two more times: (Potatoes, sauce. Potatoes, sauce).
  • Cover and bake for 1 hour.
  • Uncover and bake for 30 minutes. Optional: Broil at 425°F for 1-2 minutes to add more color to the top if desired. Watch it carefully during this time.
  • Remove from the oven and let it rest for 5-10 minutes prior to serving. Garnish with chives and serve!

Notes

Pro Tips:
  • Potatoes: Use russets! They have a high starch content which thickens the sauce as they cook. They also absorb the sauce during cooking which is necessary- it makes them more flavorful and there is plenty of sauce to be absorbed. Yukon Golds are the next best option. Avoid waxy potatoes like red potatoes, they won't absorb or thicken the sauce. 
  • Slice the potatoes thin: I'd almost call them paper thin (1/8th of an inch). This ensures they cook through all the way through. 
  • Use a Mandoline: This is the quickest and most accurate way to get thin, even slices. Use it with caution:Use every safety measure and safety tool provided and then some. They are very sharp and it's easy to cut your fingers. (Trust me.)
  • Cheese: a 6 oz. block of Gruyere is enough to make 2 cups shredded. (I use 5.5 oz. of the block) I use Emmi Le Gruyère Cheese and Belgioioso Parmesan. Fontina Cheese makes a great addition to this as well. Cheddar can be used if needed, but I'd recommend Gruyere if at all possible.
  • Shred/Grate the cheese from a block. Don't use packaged shredded/grated cheese as it won't melt as well or taste as good.
  • Garlic- Definitely use fresh cloves for this recipe (vs. jarred).
  • Sauce: Keep two things in mind: 1.) It's thin at first, but thickens more and more as the dish cooks. 2.) There is a lot of it, but the potatoes continue to absorb it during cooking, and some of it evaporates when it's cooked without the cover. 
Make-Ahead Method:
  • Assemble as outlined and bake at 350° for 45 minutes. Let it cool completely, then cover and refrigerate for up to 2 days. (It will be very saucy and still on the thin side.)
  • When ready to serve: Let it sit out at room temperature for 1 hour. Bake covered at 350° for 20 minutes. Remove cover and bake for 30 more minutes, or until bubbly and hot. Broil for 1 minute at the end if desired.
Storage:
  • Store in an airtight container and refrigerate for up to 5 days. While leftovers can be frozen, they don't reheat exactly back to their original consistency.
Nutritional information is an estimate and is per serving. This recipe makes 12 servings.

Nutrition

Calories: 355kcal, Carbohydrates: 21g, Protein: 11g, Fat: 26g, Saturated Fat: 16g, Polyunsaturated Fat: 1g, Monounsaturated Fat: 7g, Trans Fat: 0.1g, Cholesterol: 81mg, Sodium: 321mg, Potassium: 493mg, Fiber: 1g, Sugar: 3g, Vitamin A: 949IU, Vitamin C: 7mg, Calcium: 316mg, Iron: 1mg
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Course: Side Dish
Cuisine: American, French
Author: Stephanie