Scalloped Potatoes Recipe

Prepare and par-cook

Preheat the oven to 375°F (190°C). Peel the potatoes (optional) and slice them 1/8 to 1/4 inch thick using a mandoline or sharp knife for even slices. Place slices into a large bowl of cold water to prevent browning.

Bring a large pot of water to a boil and add 1 tablespoon salt. Drain the potato slices from the cold water and add them to the boiling water. Parboil for 4 minutes—potatoes should be just tender but not falling apart. Drain well and spread on a clean towel to remove excess moisture.

Infuse garlic and make roux

Finely mince or grate the garlic. In a medium saucepan over medium heat, melt 3 tablespoons unsalted butter. Add the minced garlic and cook until fragrant, about 30 seconds (don’t brown). Sprinkle in 3 tablespoons flour and cook, stirring constantly, for 1 to 1.5 minutes to make a blond roux.

Slowly whisk in 2 cups whole milk and 1 cup heavy cream, a little at a time to avoid lumps. Bring the mixture to a gentle simmer while whisking. Add 1 teaspoon dry mustard, 1 teaspoon salt, 1 teaspoon freshly ground black pepper, and 1 teaspoon fresh thyme leaves. Simmer, stirring occasionally, until the sauce thickens enough to coat the back of a spoon, about 6–8 minutes. Taste and adjust seasoning.

Layer potatoes and cheese

Butter a 9x13-inch baking dish lightly. Arrange a single overlapping layer of potato slices across the bottom. Sprinkle about one-third of the shredded sharp cheddar and a few tablespoons of grated Parmesan over the potatoes. Pour about one-quarter of the cream sauce evenly over the layer. Repeat two more times (potatoes, cheeses, sauce), finishing with the remaining potatoes and pouring any leftover sauce over the top. Evenly sprinkle the remaining cheddar and parmesan on top.

Prepare breadcrumb topping

In a small bowl, combine 1 cup panko breadcrumbs with 2 tablespoons melted butter until moistened. Sprinkle the breadcrumb mixture evenly over the top cheese layer.

Cover the baking dish loosely with foil and bake in the preheated 375°F (190°C) oven for 30 minutes. Remove the foil and continue baking for another 20–25 minutes, until the top is golden and the sauce is bubbling around the edges and a knife slides easily into the potatoes.

Remove the scalloped potatoes from the oven and let rest for 10–15 minutes to allow the sauce to set. Sprinkle with 2 tablespoons thinly sliced fresh chives and additional black pepper to taste. Serve warm.