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freshly made potatoes au gratin in a casserole dish.
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4.52 from 31 votes

Potatoes Au Gratin

A classic dish of Potatoes Au Gratin, that will have you hooked at first bite. They're perfect for your Holiday table or even just a Sunday supper. Thinly sliced potatoes, smothered in a creamy sauce and topped with cheddar and Parmesan cheese. So good to the very last bite!
Prep Time20 mins
Cook Time1 hr 45 mins
Total Time2 hrs 5 mins
Course: Dinner, Side Dish
Cuisine: American
Keyword: potatoes au gratin, scalloped potatoes
Servings: 8
Calories: 385kcal

Ingredients

  • ¼ cup butter unsalted
  • 1 medium onion chopped
  • 3 cloves garlic minced
  • ¼ cup all-purpose flour
  • 1 cup chicken broth low sodium or no sodium added
  • 2 cups whole milk or half and half
  • ½ teaspoon salt or to taste
  • ½ teaspoon pepper or to taste
  • 1 tablespoon fresh thyme chopped, for garnish
  • 3 pounds potatoes sliced into ⅛-inch rounds, I prefer Yukon Gold
  • 2 cups white cheddar cheese freshly grated
  • ½ cup Parmesan cheese freshly grated

Instructions

  • Preheat the oven: Preheat the oven to 350°F. Lightly spray a 9x13-inch casserole dish with cooking spray.
  • Sauté onion and garlic: In a medium size skillet, melt the butter over medium low heat. Add the onion and garlic and cook for about 3 minutes until softened. Sprinkle the flour over the onion and garlic and stir. Cook for 2 more minutes.
  • Make the sauce: Slowly add the chicken broth and milk while continuously whisking to thicken. Whisk until smooth. Bring to a boil over medium heat while continuing to whisk. Season with salt and pepper.
  • Layer the ingredients: Layer about a pound of the potato slices on the bottom of the prepared casserole dish. Top evenly with ⅓ of the sauce and about ½ cup of cheddar cheese. Repeat with another layer of potatoes, ⅓ of the sauce, and ½ cup of cheddar, the rest of the potatoes, remaining sauce, remaining cheese and finally the Parmesan cheese.
  • Bake: Cover the casserole dish with aluminum foil and bake for about 45 minutes. Remove the aluminum foil and bake for an additional 45 minutes or until golden brown and the potatoes are fork tender. If needed, broil for a couple minutes until golden brown to your preference.
  • Garnish and serve: Garnish with fresh chopped thyme and serve with your favorite meat dish.

Notes

  1. Use the right potato. You want a potato that will hold its shape but still bake tender. This is why Yukon Gold potatoes or red potatoes work well.
  2. Make ahead tip: Prepare everything up to and including step 5, cover with foil and refrigerate over night. The next day when ready to bake preheat the oven and bake as instructed.
  3. Always buy whole blocks of cheese and grate them yourselves. While store-bought shredded cheese is more convenient, it contains preservatives and chemicals.
  4. Layer the potatoes, sauce and cheese for even baking, rather than placing all the potatoes at once, pouring sauce over them and topping with cheese. Also by layering, we're making sure all the potatoes are evenly coated in this wonderful sauce.
  5. Store leftover potatoes in an airtight container in the fridge for up to 4 days.
  6. Freezing potatoes au gratin may cause the texture and flavor to change. However, if you must freeze them, store them in an airtight container and freeze them for up to 2 weeks for best results. You can also freeze them in the dish they were baked in, but cover it tightly with aluminum foil or plastic wrap.

Nutrition

Serving: 1serving | Calories: 385kcal | Carbohydrates: 38g | Protein: 16g | Fat: 19g | Saturated Fat: 12g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Trans Fat: 1g | Cholesterol: 55mg | Sodium: 468mg | Potassium: 893mg | Fiber: 4g | Sugar: 5g | Vitamin A: 654IU | Vitamin C: 36mg | Calcium: 380mg | Iron: 2mg