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Au Gratin Potatoes

These decadent Au Gratin Potatoes are the ultimate side dish for any special occasion. They feature thinly sliced potatoes smothered with a rich homemade cream sauce and the robust flavor of Gruyere cheese. They’re heavenly.


Easy Au Gratin Potatoes Recipe

Have you ever wondered the difference between scalloped potatoes and au gratin potatoes? Food purists will tell you that scalloped potatoes recipes don’t include cheese and are basically thin potatoes cooked in a cream sauce making them more simple by nature. Au gratin potatoes tend to be a bit more decadent and the recipe is a bit more involved typically layered with lots of cheese. I have used the terms interchangeably from time to time and tend not to get too terribly fussy about the titles of my potato recipes. We’re an equal opportunity potato loving family so regardless of what they’re called to us, it all spells delicious. How to make authentic Au Gratin Potatoes:

  • Potatoes – Russet potatoes (peel intact) cut into 1/8 inch slices.
  • Sauce – Salted butter, onion finely diced, all purpose flour, salt, black pepper, ground mustard, ground nutmeg, garlic finely minced.
  • Herbs – One tablespoon fresh thyme leaves, plus additional for garnishing.
  • Milk – Whole milk or half and half.
  • Cheese – Shredded Gruyere cheese.
  • Topping – Gruyere plus grated Parmesan cheese.

How to Make the Best Au Gratin Potatoes

  • Ingredients you’ll need to make homemade Au Gratin Potatoes: 3 1/2 to 4 pounds thinly sliced russet potatoes (peel intact), all purpose flour, butter, milk, salt, black pepper, nutmeg, fresh thyme, shredded Gruyere cheese, Parmesan cheese, finely diced onion and minced garlic.
  • Kitchen tools you’ll need: A 3 quart baking dish either oval or rectangular, a mandolin or food processor, whisk, measuring cups and spoons, heavy bottomed saucepan, cheese grater, sharp knife and cutting board.
  • The potato slices for au gratin potatoes need to be super thin. This can be done by hand but for uniform size, a mandolin or a food processor is best.
  • When layering the potatoes, you should overlap them as you arrange them in the dish. You could use an oval dish as I did or a 13 x 9 inch rectangular dish or pan.
  • The homemade sauce for these potatoes features a hint of garlic. You can adapt the flavor using more garlic, if that’s your preference. In this application, it doesn’t have to be a bold flavor but it’s main role is that of enhancing and not dominating, the flavor of the sauce.
  • Since the potatoes are raw in this recipe, it’s not ideal to make it in advance and chill until baking.
  • If you choose to slice the potatoes by hand, have nearby a large bowl filled with cold water. Place sliced potatoes in the water to keep them from turning brown while you work. Drain well and pat dry before assembling the casserole.
  • I use Gruyere cheese for this recipe. As always, you could adapt using another variety of cheese according to your taste or what you have on hand. For special occasions, Gruyere is the way to go.
  • Store baked Au Gratin Potatoes chilled in the refrigerator for up to 3 days. Reheat in single servings in the microwave or in a 350°F oven just until heated through. Lay a piece of foil on top.

More Easy Potato Recipes to Make




Helpful Kitchen Items:

Au Gratin Potatoes

Prep Time25 minutes
Cook Time1 hour
Stand time10 minutes
Total Time1 hour 35 minutes
Course: Side Dish
Cuisine: American
Keyword: au-gratin-potatoes, best-au-gratin-potatoes-recipe
Servings: 10 servings (may vary)
Calories: 328kcal


  • 3 1/2-4 lbs russet potatoes (peel intact) 1/8 inch slices
  • 4 Tbsp salted butter
  • 1 small onion finely diced
  • 3 Tbsp all purpose flour
  • 1 tsp salt
  • 1 tsp black pepper
  • 1/2 tsp ground mustard
  • 1/8 tsp ground nutmeg
  • 1 large clove garlic finely minced
  • 1 Tbsp fresh thyme leaves plus additional for garnishing
  • 2 cups whole milk or half and half
  • 2 cups shredded Gruyere cheese divided use
  • 1/4 cup grated Parmesan cheese, plus 2-3 Tbsp for the top


  • Preheat oven to 375°F. Butter an 11 x 8 inch (2.5 quart baking dish) or similar size baking dish with 1 Tablespoon of butter. Set aside.
  • Thoroughly clean potatoes and using a mandolin slice 1/8 inch slices.
  • To make sauce: In a heavy bottomed saucepan, melt butter over medium heat. Add onion, cooking for 1-2 minutes or just until softened. Add garlic, cook for 1 minute. Add flour, stir until butter is absorbed.
  • To the flour add salt, black pepper, ground mustard and nutmeg. Gradually whisk in milk. Add thyme. Bring to a light bubble then immediately lower the heat to simmer for 3-5 minutes, stirring occasionally.
  • Remove from heat. Add 1 cup Gruyere and 1/4 Parmesan cheese to sauce, Mix until melted.
  • To assemble: Layer 1/2 potato slices fanned and overlapping in baking dish. Spread 1/2 sauce evenly over potatoes.
  • Repeat remaining potatoes, spread with sauce. Sprinkle top with remaining Gruyere and sprinkle with 3 Tablespoons of Parmesan.
  • Cover with foil and bake for 50-60 minutes. Uncover, increase oven temperature to 400 °F. Bake for another 20 minutes or until the top is golden and the potatoes are fork tender.
  • Let stand 5-10 minutes of the sauce to thicken then serve garnished with fresh thyme.


Serving: 1serving | Calories: 328kcal | Carbohydrates: 34g | Protein: 14g | Fat: 16g | Saturated Fat: 9g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 4g | Trans Fat: 0.2g | Cholesterol: 49mg | Sodium: 528mg | Potassium: 784mg | Fiber: 2g | Sugar: 4g | Vitamin A: 527IU | Vitamin C: 11mg | Calcium: 377mg | Iron: 2mg
Tried this recipe?Mention @melissassk or tag #melissassk!


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