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Sweet potato-russet potato gratin with horseradish and Dijon crust

Sweet potato - russet potato gratin recipe

Susan Selasky for the Detroit Free Press

Here’s a recipe to please both sweet potato lovers and regular potato fans!

To make this in advance, cool the cooked components of the gratin before combining and assembling. Leave off the topping. Bring to room temperature, about 45 minutes, before topping with bread crumb mixture and baking.

Sweet potato-russet potato gratin with horseradish and Dijon crust

Yield 8



  • 1-1/2 cups lightly toasted panko bread crumbs or coarse fresh bread crumbs
  • 2 tablespoons unsalted butter, melted
  • Pinch of kosher salt
  • 1 tablespoon Dijon mustard
  • 2 tablespoons Parmesan cheese or Parmigiano-Reggiano
  • 2 tablespoons chopped fresh flat-leaf parsley


  • 2 tablespoons unsalted butter, plus 1/2 teaspoon for the dish
  • 1 cup thinly sliced shallots (6-7 large)
  • 2/3 cup heavy whipping cream
  • 2/3 cup fat-free, reduced-sodium canned chicken broth
  • 2 tablespoons prepared horseradish
  • Kosher salt
  • Freshly-ground black pepper
  • 1 large russet potato (12 ounces), peeled
  • 1 large sweet potato (12 ounces), peeled
  • 1/3 cup grated Parmesan cheese or Parmigiano-Reggiano


In a bowl, combine all the topping ingredients and set aside.

To prepare the gratin: Preheat the oven to 350 degrees. Butter a shallow 2-quart gratin dish with 1/2 teaspoon of the butter.

In a small saucepan, melt the remaining 2 tablespoons butter over medium heat. Add the shallots and a big pinch of salt; cook, stirring frequently, until softened, limp and somewhat golden.

Whisk together the cream, broth and horseradish; add to the shallots. Season with salt and pepper, stir to combine and take off the heat.

Peel both potatoes. Cut each in half lengthwise, and slice each across into thin half moons. In a large bowl, combine the potato and sweet potato slices, 2 teaspoons salt, Parmesan and shallot cream. Mix gently but thoroughly and scrape into the prepared gratin dish, smoothing and pressing until evenly distributed. Cover with the bread crumb topping.

Bake until the crust is deep golden brown, the juices around the edges have subsided and the potatoes are tender when pierced with a fork, about 1 hour. Remove from oven and let rest for 15 minutes before serving.


Nutrition information per serving: 280 calories (48% from fat), 15 grams fat (9 grams sat. fat), 32 grams carbohydrates, 6 grams protein, 790 mg sodium, 45 mg cholesterol, 3 grams fiber.

Recipe adapted from Tested by Susan Selasky for the Detroit Free Press Test Kitchen.

Gratin dish photographed by Jarrad Henderson in the Detroit Free Press studio on Thursday, November 1, 2012 in Detroit, Michigan.

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