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Scalloped Potatoes

Scalloped potatoes made with thinly layered russet slices baked in a garlic-butter cream sauce until golden and fork-tender. Covered bake for creamy tenderness, then uncovered for a browned top and melted Parmesan finish.
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Prep Time 25 minutes
Cook Time 1 hour 30 minutes
resting 15 minutes
Total Time 2 hours 10 minutes
Servings: 8 servings
Course: Side Dish
Cuisine: American
Calories: 570
Ingredients Equipment Method Notes

Ingredients
  

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

Equipment

  • 1 sheet pan
  • 1 cast iron skillet

Method
 

Prep and preheat
  1. Preheat the oven to 375F, then butter a 9x13-inch baking dish. Use a thin layer of butter so the potatoes release cleanly.
Make the garlic cream sauce
  1. Melt the butter, then cook the garlic for 30 seconds. The garlic should be fragrant but not browned.
  2. Whisk in the all-purpose flour for 1 minute. Keep whisking until it looks slightly smoother and cooked.
  3. Gradually whisk in the whole milk and heavy cream, then simmer until slightly thickened. Stir often so the mixture stays silky and smooth.
  4. Season with salt, black pepper, and fresh thyme leaves. Taste and adjust so the sauce is well-seasoned.
Layer and bake
  1. Layer the potatoes and onion in the dish in three layers. Aim for even thickness so they bake uniformly.
  2. Pour sauce over each layer as you build the casserole. Make sure the potatoes are well coated between layers.
  3. Cover with foil, then bake for 1 hour at 375F. Look for bubbling at the edges before moving to the next step.
  4. Uncover, sprinkle with Parmesan, and bake 25-30 minutes at 375F until golden and fork-tender. The top should be browned and the potatoes should feel soft when pierced.
Rest and serve
  1. Rest the scalloped potatoes for 15 minutes before serving. This helps the sauce set so each slice holds its layers.

Notes

For clean, even layers, slice the potatoes consistently at about 1/8 inch thick and build the dish in three stacks, pouring sauce over each one. Refrigerate leftovers in a covered container for up to 4 days; reheat in a 350F oven until hot throughout. Freezing is not recommended because the dairy sauce can split when thawed and reheated. For a lighter option, use half-and-half in place of the heavy cream while keeping the same baking times.