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5 from 4 votes

Cheesy Au Gratin Potatoes

Layers of thinly sliced potatoes and onions covered in a cheesy cream sauce make these Homemade Au Gratin Potatoes amazing!
Prep Time30 mins
Cook Time1 hr
Total Time1 hr 30 mins
Course: Side Dish
Cuisine: American
Servings: 12
Calories: 314kcal
Author: Julie Evink


  • 3 pounds yellow potatoes thinly sliced (about 12-14 potatoes)
  • 1 yellow onion thinly sliced
  • 3 ½ Tbsp unsalted butter
  • 3 ½ Tbsp all-purpose flour
  • 1 tsp salt
  • 1 tsp garlic powder
  • ½ tsp onion powder
  • ½ tsp dried basil
  • ¼ tsp dried rosemary
  • ¼ tsp pepper
  • 2 c. heavy cream
  • 1 ¼ c. sharp cheddar cheese
  • Parsley chopped (optional garnish)


  • Preheat the oven to 400 degrees Fahrenheit. Prepare a 9X13 baking dish by spraying it with cooking spray.
  • Place one layer of sliced potatoes on the bottom of the baking dish. Sprinkle on ¼ of the sliced onions on top of the potato layer. Repeat with the potatoes and onions until you have used all of the potatoes and onions. Set aside.
  • In a medium saucepan over medium high heat, melt the unsalted butter and whisk in the flour. Continue to whisk for one to two minutes.
  • Add in the garlic powder, onion powder, dried basil, dried rosemary, and pepper. Whisk together.
  • Slowly whisk in the heavy cream and cook until thickened, stirring frequently.
  • Dump all the cheese into the saucepan and mix until the cheese is completely combined.
  • Pour the cheese sauce over the potatoes and onions in the baking dish.
  • Cover the pan with aluminum foil and bake in the oven for 50 minutes.
  • Take off foil and return pan to oven for an additional 10 minutes or until the top is set and the sides are bubbly.
  • Garnish with chopped parsley (optional) and then plate and serve. Best when served warm.


How long do leftovers keep?
Keep them in an airtight container in the refrigerator and they will store well for up to four days. Keep in mind that it won’t be as creamy when you reheat it because the sauce will thicken when chilled.
Can you freeze it?
You can freeze the leftovers for up to two weeks. Thaw in the refrigerator before rewarming.
Can you make it ahead?
For the best creamy cheese sauce, I think it’s best to make this dish and serve it straight from the oven. For this reason, I don’t recommend making it ahead.
Slicing Tip: The thickness of the sliced potatoes matters. If they are sliced thicker they will take longer to bake. Also, if they are sliced unevenly they may not bake evenly. This is why I use a mandolin, it makes it so much easier to evenly them.
Layering Tip: The easiest way to layer the potatoes and onions is to layer the potato slices flat with the onions on top. The tradeoff is that you won’t get crispy potatoes on top of the dish once it’s baked but it’s still really delicious.
For a fancier presentation, you can line the sliced potatoes up like books on a bookshelf with onion slices in between. This will take much longer but the tops of the potatoes will get crispier when baked.
Garnish Tips: Feel free to add a little more shredded cheese on top before you bake it or sprinkle some buttered breadcrumbs over the top for a crispy top. You can also garnish with fresh chopped chives instead of parsley.


Calories: 314kcal | Carbohydrates: 24g | Protein: 6g | Fat: 22g | Saturated Fat: 14g | Trans Fat: 1g | Cholesterol: 75mg | Sodium: 290mg | Potassium: 541mg | Fiber: 3g | Sugar: 1g | Vitamin A: 806IU | Vitamin C: 23mg | Calcium: 129mg | Iron: 1mg