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Cheesy Au Gratin Potatoes

Cheesy au gratin potatoes layer thinly sliced Yukon Gold potatoes with a creamy sharp cheddar sauce. They bake under foil until tender, then uncover to develop a golden-brown top.
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Prep Time 20 minutes
Cook Time 1 hour 32 minutes
resting 15 minutes
Total Time 2 hours 7 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: American
Calories: 625
Ingredients Equipment Method Notes

Ingredients
  

For the potatoes
  • 1 tbsp unsalted butter for greasing the baking dish
  • 3 lb Yukon Gold potatoes peeled and sliced 1/8 inch thick
  • 1 tsp kosher salt
  • 0.5 tsp black pepper
For the cheese sauce
  • 3 tbsp unsalted butter
  • 2 cloves garlic minced
  • 3 tbsp all-purpose flour
  • 2 cups whole milk
  • 1 cup heavy cream
  • 0.25 tsp kosher salt
  • 2 cups sharp cheddar cheese shredded, divided

Equipment

  • 1 9x13-inch baking dish

Method
 

Prepare the potatoes
  1. Preheat the oven to 375°F.
  2. Grease a 9x13-inch baking dish with the 1 tablespoon butter.
  3. Arrange half the potatoes in the dish, overlapping the slices.
  4. Season with half the salt and pepper.
  5. Repeat with the remaining potatoes and season with the remaining salt and pepper.
Make the cheese sauce
  1. Melt the 3 tablespoons butter in a medium saucepan over medium heat, add the garlic, and cook for 30 seconds.
  2. Whisk in the flour and cook for 1 minute.
  3. Gradually whisk in the milk and heavy cream.
  4. Whisk in the 1/4 teaspoon salt.
  5. Cook, stirring, for 4 to 6 minutes until the sauce is bubbling and thick enough to coat a spoon.
  6. Remove the saucepan from the heat and stir in 1 1/2 cups of the cheddar until melted.
Assemble and bake
  1. Pour the cheese sauce evenly over the potatoes.
  2. Sprinkle with the remaining 1/2 cup cheddar.
  3. Cover the dish tightly with foil and bake for 50 to 60 minutes.
  4. Uncover and bake for 25 to 35 minutes more, until a knife slides easily into the potatoes and the top is golden brown.
  5. Let the potatoes rest for 15 minutes before serving.

Notes

Slice the potatoes evenly so they cook at the same rate. Refrigerate leftovers for up to 4 days; freezing is not recommended because the creamy sauce may separate. For a gluten-free option, substitute a cup-for-cup gluten-free flour blend.