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Scalloped Potatoes

Scalloped Potatoes with creamy garlic sauce are baked until tender, layered, and topped with a golden Parmesan crust. Thin 1/8-inch potato slices and a flour-thickened milk/cream base create a sliceable, comforting side dish.
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Prep Time 25 minutes
Cook Time 1 hour 30 minutes
Rest 15 minutes
Total Time 2 hours 10 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: American
Calories: 520
Ingredients Equipment Method Notes

Ingredients
  

Potatoes
  • 3 lb russet potatoes peeled and sliced 1/8 inch thick
  • 1 onion thinly sliced
Creamy sauce
  • 4 tbsp butter
  • 3 cloves garlic minced
  • 0.25 cup all-purpose flour
  • 3 cup whole milk
  • 1 cup heavy cream
Seasoning & topping
  • 2 tsp salt
  • 0.5 tsp black pepper
  • 1 tsp fresh thyme leaves
  • 0.5 cup Parmesan grated

Equipment

  • 1 sheet pan

Method
 

Prep & preheat
  1. Preheat the oven to 375F, then butter a 9x13-inch baking dish until lightly coated.
  2. Peel and slice russet potatoes to 1/8 inch thickness, and thinly slice the onion.
Make the garlic cream sauce
  1. Melt butter in a pan, then cook minced garlic for 30 seconds, stirring until fragrant.
  2. Whisk in all-purpose flour and cook for 1 minute to remove the raw flour taste.
  3. Gradually whisk in whole milk and heavy cream, then simmer until slightly thickened, stirring until the sauce coats the back of a spoon.
  4. Season the sauce with salt, black pepper, and fresh thyme leaves, stirring until evenly combined (steam should be gentle and steady).
Layer & bake
  1. Layer potatoes and onion in the dish in three layers, then pour sauce over each layer so the slices are partially submerged.
  2. Cover with foil and bake for 1 hour, until the potatoes are mostly tender when pierced.
  3. Uncover, sprinkle grated Parmesan over the top, and bake 25-30 minutes until the surface is golden and a fork slides through the potatoes easily (golden cue: browned edges and top spots).
Rest & serve
  1. Rest the scalloped potatoes for 15 minutes before serving so the sauce thickens and layers hold together.

Notes

Pro tip: slice the potatoes to 1/8 inch for even tenderness—thicker slices can stay firm by the time the top browns. Store covered in the refrigerator up to 4 days; reheat in a 350F oven until warmed through. Freezing is not recommended because the creamy sauce can loosen after thawing. For a lighter option, use half-and-half instead of the heavy cream (texture will be slightly less rich).