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Baking dish of a potato gratin with poblano peppers, topped with breadcrumbs.
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4.93 from 13 votes

Classic Potato Gratin (with Poblanos)

Classic potato gratin recipe with tips for choosing the best kind of potato, cheese, and how to make it creamier.
Prep Time20 minutes
Cook Time1 hour 15 minutes
steeping15 minutes
Total Time1 hour 50 minutes
Course: Vegetable Side
Cuisine: Any
Keyword: poblano au gratin potatoes, potatoes au gratin
Servings: 8 servings
Calories: 218.1kcal
Author: Susan Pridmore

Equipment

Ingredients

  • 2 tablespoons unsalted butter, room temperature, divided
  • 1 medium shallot, peeled and thinly sliced
  • 1 tablespoon garlic paste, or 3 garlic cloves, peeled, smashed and minced
  • 2 cups heavy cream
  • ½ cup whole milk
  • 1 teaspoon Better Than Bouillon paste
  • 1 teaspoon dijon mustard
  • ½ teaspoon kosher salt, or ¼ teaspoon table salt
  • ¼ teaspoon freshly ground black pepper
  • 10 sprigs fresh thyme
  • 1 poblano pepper
  • 4 pounds Yukon potatoes, unpeeled
  • 3 ounces grated Gruyère cheese, about 1 ¼ cup
  • 1 ounce grated Parmesan, about ¼ cup
  • 2 tablespoons toasted breadcrumbs

Instructions

  • Preheat the oven to 350˚F. Smear ½ tablespoon butter all over the inside of a 9" X 13" baking dish. Set aside.
  • Melt the remaining butter in a medium pot over medium heat. Add the sliced shallot and garlic and sauté for 5 minutes.
  • Stir in the cream and milk. Add the bouillion, mustard, salt, pepper and thyme sprigs. Simmer for 15 - 20 minutes, until reduced by ¼ cup. Let cool and remove the thyme.
  • Roast the poblano pepper on a baking sheet under a broiler until the skin blisters, turning as needed. This should take about 15 minutes. Place in a jar or plastic bag. Seal and wait for 10 minutes. Remove the pepper and peel. Slice open, scrape out the seeds, and dice.
  • Thinly slice the potatoes, approximately ⅛" thick. I use a hand-held mandolin, and set it on #2 setting.
  • Arrange the potato slices like shingles on the bottom of the baking dish until the bottom is covered. Lightly salt and pepper the potatoes, and sprinkle ⅓ of the Gruyere cheese and ⅓ of the diced poblanos over the slices.
  • Repeat for 2 more layers, finishing with the final ⅓ of the Gruyere and poblanos. Pour the cream reduction over the potatoes. Cover the baking dish tightly with foil. Bake for 60 - 75 minutes, until the potatoes are tender. If baking this at 5000-7000 feet, you may need to bake it for 75 - 85 minutes.
  • Uncover, sprinkle with Parmesan and toasted breadcrumbs, if using. Bake for an additional 10 minutes.
  • Serve piping hot.

Nutrition

Calories: 218.1kcal | Carbohydrates: 42.5g | Protein: 5.2g | Fat: 3.6g | Saturated Fat: 2.1g | Polyunsaturated Fat: 0.3g | Monounsaturated Fat: 0.8g | Trans Fat: 0.1g | Cholesterol: 8.4mg | Sodium: 284.6mg | Potassium: 980.8mg | Fiber: 5.4g | Sugar: 2.2g | Vitamin A: 1238.3IU | Vitamin C: 47.1mg | Calcium: 41.2mg | Iron: 2.2mg