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4.36 from 28 votes

The Best Potato Gratin Recipe

This is the BEST Potato Gratin Recipe! Made with thinly sliced Yukon Gold potatoes that are layered in a silky smooth cheese sauce then baked until lightly golden brown. This is the perfect side dish for any occasion!
Prep Time20 minutes
Cook Time1 hour 20 minutes
Total Time1 hour 45 minutes
Course: Side Dish
Cuisine: American
Keyword: au gratin potatoes, potato grain recipe, potato gratin, scalloped potatoes, yukon gold poatatoes
Servings: 8 servings
Author: Kathryn Donangelo

Ingredients

  • 2.5 lbs. Yukon Gold Potatoes; peeled and thinly sliced I highly recommend using a mandolin
  • 2 Tbsp. butter
  • 1/2 cup yellow onions; chopped
  • 2 Tbsp. all-purpose flour
  • 2 cups whole milk or cream
  • 1 cup sharp cheddar cheese; shredded
  • 1 cup gruyere cheese; shredded
  • 1/2 cup Monterey Jack cheese; shredded
  • 1/2 tsp. salt
  • 1/2 tsp. black pepper
  • 2 cloves garlic; minced
  • 1 tsp. fresh or dried thyme
  • 1/2 cup low-sodium chicken broth

Instructions

  • Preheat the oven to 400 degrees F. Spray a 9x9 inch square baking dish (you could also use an 8x12 or 9x13 inch dish) with nonstick cooking spray or grease with butter or oil.

Make the cheese sauce

  • In a medium saucepan on medium heat, cook butter and onions until butter has meted. Whisk in flour. Once it has thickened, add milk, cheeses, salt, pepper, garlic and thyme. Vigorously whisk for a few minutes making sure there isn't any lumps. Add in chicken broth and whisk again. Bring cheese sauce to a simmer for a few minuets. It should be creamy and the consistency should resemble a gravy.

Assemble Potato Gratin

  • Add 1/3 of the sliced potatoes in the baking dish. You can layer the potatoes in rows or scatter them. Pour 1/3 of the cheese sauce mixture evenly over the potatoes and repeat with the next 2 layers.
  • Cover the baking dish with foil and bake for 40 minutes.
  • Remove the foil and sprinkle more cheese (about 1 cup of total of cheddar, Jack and gruyere). Reduce the oven temperature to 350 degrees F. Return the baking dish to the oven and bake for another 40 minutes. The potatoes will be lightly golden brown when done and you will be soft. Let cool for a few minutes and enjoy!

Notes

  1. Use a mandolin slicer to cut the potatoes extra thin.  I like to slice my potatoes to 1/8 of an inch in thickness and a mandolin does this quickly and efficiently. 
  2. To speed up the baking process, microwave the sliced potatoes for 5-10 minutes to slightly soften prior to assembly.  You can also boil the sliced potatoes for approximately 5 minutes or until soft and drain. 
  3. To speed up the prep of this dish, slice the potatoes ahead of time.  Keep sliced potatoes in a bowl full of ice-cold water in the fridge and pat dry when ready to use.  Will keep for up to 24 hours ahead of time.  
  4. For best results, always grate your own cheese.  Store bought pre-shredded cheeses have an anti-caking agent added which prevents cheese from melting as well as it should.