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A spoon scooping up cheesy scalloped potatoes from a casserole dish.
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Cheesy Scalloped Potatoes

Learn how easy it is to make Cheesy Scalloped Potatoes from scratch! This recipe has decadent caramelized onions in a creamy cheddar cheese sauce with simple seasonings.
Prep Time10 minutes
Cook Time1 hour 40 minutes
Total Time1 hour 50 minutes
Course: Side Dish
Cuisine: American
Servings: 8 people
Calories: 464kcal
Author: Stephanie

Ingredients

  • 6 tablespoons butter separated
  • 1 Tablespoon olive oil
  • 1 large yellow onion
  • ½ teaspoon dried thyme
  • 2 cloves garlic minced
  • 4 tablespoons flour
  • 3 cups milk
  • 3 ½ cups shredded orange cheddar cheese divided
  • 2 Tablespoons cream cheese softened
  • ½ teaspoon mustard powder
  • ½ teaspoon salt
  • ¼ teaspoon pepper
  • 1 pinch cayenne pepper
  • 2.5 lbs. Yukon Gold or Russet Potatoes about 6 medium potatoes

Instructions

  • Preheat oven to 350°.
  • Note: While the onions caramelize, measure out your remaining ingredients.
  • Soften/Caramelize the Onions: Cut the onions into ¼ inch strings. Melt 2 tbsp. butter and olive oil in a large skillet over medium-low heat. Add the onions and thyme. Let them cook slowly for about 30 minutes, until they’re brown and caramelized. Stir every few minutes. Once done, remove and set aside.
  • Combined Butter & Flour: Increase heat to medium. Add 4 tbsp. butter to the pot along with the garlic. Cook for 1 minute and use a silicone spatula to “clean” the bottom and sides of the pot. Add flour and whisk to incorporate. Continue to whisk for 1 minute or until you can no longer smell flour.
  • Add the Milk: Gradually add the milk, splashes at a time, and whisk to incorporate. If you add it too fast the roux will thin out too much. Bring to a boil, then remove from heat.
  • Add Seasonings: Add mustard powder, salt, pepper, and cayenne. Stir to combine.
  • Add Cheese: Let the roux cool down a bit. Reserve 1 heaping cup of cheddar cheese and gradually sprinkle the rest in. If the base is too hot when the cheese is added, the dairy will separate and the sauce will be grainy
  • Stir in cream cheese, then add the caramelized onions.
  • Slice the potatoes: Peel the potatoes, rinse, and pat dry. Cut them into thin and even slices, about 1/8 inch thick. (See post for visual.)
  • Fill the Casserole Dish: Arrange half of them on the bottom of a lightly greased 9 x 13-inch baking dish and top with half of the cheese sauce. Add remaining potatoes and remaining cheese sauce. Top with remaining cheddar cheese.
  • Bake: Cover and bake at 350° for 45 minutes. Remove cover and bake for 40 more minutes, until the potatoes are tender.
  • Optional: Broil at 400° until the top is slightly browned, don't walk away. Let sit for 5-10 minutes, garnish with fresh parsley, and serve.

Notes

Pro Tips:
  • Caramelizing the onions is optional but adds a really nice sweet offset to the savory flavors in this dish. To save time, you can simply soften them, or even just caramelize them slightly.
  • Shred the cheese from a block, packaged cheese contains cellulose which doesn’t allow it to melt as well. It also doesn’t taste as fresh.
  • Instead of using all cheddar, you can also use gruyere which pairs nicely with the caramelized onions. Mozzarella and Parmesan are good additions as well.
  • This recipe makes a lot of sauce, but the potatoes absorb a lot of the sauce as they bake and even after they come out of the oven, so this ensure that they remain nice and cheesy. Especially if you have leftovers.
  • Try my Au Gratin Potatoes if you prefer a sauce that's not thickened with flour! It also has Gruyere and Parmesan cheese instead of cheddar and cream cheese.
Crock Pot Method:
  • Prepare sauce and slice the potatoes as outlined and layer them in a lightly greased Slow Cooker. Top with cheese.
  • Heat on low for 7-8 hours.
Make-Ahead Method:
  • Assemble the potatoes as outlined but don't top with remaining cup of cheddar cheese yet. Cover and bake for 45 minutes at 350°. Let it cool completely. Cover and refrigerate for up to 3 days.
  • When ready to serve top with 1 cup of cheese. Cover and bake it at 350° for 55 minutes. If desired, remove the cover at the end and broil at 450° for up to 5 minutes to brown the top.

Nutrition

Calories: 464kcal | Carbohydrates: 34g | Protein: 19g | Fat: 28g | Saturated Fat: 17g | Trans Fat: 1g | Cholesterol: 80mg | Sodium: 563mg | Potassium: 802mg | Fiber: 4g | Sugar: 7g | Vitamin A: 878IU | Vitamin C: 29mg | Calcium: 489mg | Iron: 2mg