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Sweet Potato Gratin with Smoked Gouda and Rosemary Recipe

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★★★★★

4.8 from 60 reviews

This Sweet Potato Gratin with Smoked Gouda and Rosemary is a rich and comforting casserole perfect for holidays or any cozy meal. Thinly sliced sweet potatoes are baked in a fragrant, creamy sauce infused with garlic, fresh rosemary, smoked paprika, and nutmeg, layered with a blend of smoked gouda, Colby Jack, and asiago cheeses. The gratin is baked until tender and golden, resulting in a luscious dish that pairs beautifully with roasted meats or can stand alone as a vegetarian main or side.

Ingredients

Scale

Sweet Potatoes

  • 3 lbs sweet potatoes, peeled, rinsed, and thinly sliced into ⅛” rounds (mandoline slicer preferred)

Sauce and Seasonings

  • 4 tablespoons butter
  • 2 cloves garlic, minced or pressed
  • 1 small red onion, finely diced
  • 1 tablespoon all-purpose flour
  • 1 cup heavy cream
  • 1 cup half and half, or whole milk
  • ½ tablespoon finely chopped fresh rosemary leaves
  • 1 teaspoon smoked paprika
  • ¼ teaspoon ground sage
  • ½ teaspoon Diamond Kosher salt
  • ¼ teaspoon freshly ground black pepper
  • ¼ teaspoon freshly grated nutmeg

Cheeses

  • ⅓ cup grated asiago cheese
  • 1 cup smoked gouda cheese, shredded (divided)
  • 1 cup Colby Jack cheese, shredded (divided)

Instructions

  1. Preheat Oven: Preheat your oven to 400 degrees Fahrenheit to prepare for baking the gratin.
  2. Cook Aromatics: Melt butter in a large saucepan over medium heat, then add minced garlic and diced red onion. Cook, stirring occasionally, for about 5 minutes until softened and fragrant.
  3. Add Flour: Stir in the all-purpose flour to the aromatics and cook for 1 minute, stirring occasionally to form a roux that will thicken your sauce.
  4. Make Cream Sauce: Slowly whisk in the heavy cream and half and half (or whole milk) to combine, then increase heat to medium-high. Cook for 3-4 minutes, stirring occasionally until the sauce thickens and starts to bubble. Immediately turn off the heat.
  5. Season Sauce: Stir in grated asiago cheese, fresh chopped rosemary, smoked paprika, ground sage, kosher salt, black pepper, and grated nutmeg. Remove from heat and allow to cool to room temperature to avoid curdling when combined with cheese later.
  6. Prepare Potatoes: While the sauce cools, peel and slice the sweet potatoes thinly (about ⅛ inch thick) using a mandoline slicer or a sharp knife for even cooking.
  7. Arrange Potatoes: Grease a baking dish with butter or cooking spray. Arrange the sliced sweet potatoes in a circular pattern in the dish. Alternatively, if laying flat, set aside and plan to mix with sauce before baking.
  8. Add Cheese to Sauce: Once the sauce has fully cooled, stir in half of the shredded Colby Jack cheese and half of the smoked gouda cheese. It will not melt immediately, which is expected.
  9. Combine and Pour: Pour the cheese sauce evenly over the arranged potatoes in the casserole dish or mix it with the potatoes if laid flat.
  10. Add Topping Cheese: Sprinkle the remaining half of the Colby Jack and smoked gouda cheeses evenly over the top of the dish for a golden crust.
  11. Bake Covered: Cover the dish tightly with foil and bake in the preheated oven for 45 to 50 minutes, until the potatoes are tender and can be easily pierced with a paring knife.
  12. Bake Uncovered: Remove the foil and bake for an additional 15 to 20 minutes uncovered until the top is golden brown and bubbly.
  13. Rest and Serve: Let the gratin rest for 10 to 15 minutes before serving warm to allow the sauce to set.

Notes

  • For extra browning, bake a bit longer uncovered or briefly broil if your dish is broiler safe—watch closely to prevent burning.
  • To store leftovers, cover tightly with plastic wrap or transfer to an airtight container and refrigerate for up to 3 days.
  • To reheat, cover the casserole with heavy-duty foil and warm in a 350°F oven for about 30 minutes until heated through, checking periodically to avoid overcooking.
  • Originally published on 11/02/2021, updated on 08/25/2025.

Keywords: sweet potato gratin, smoked gouda, rosemary, creamy casserole, holiday side dish, vegetarian gratin

Find it online: https://dishedbydana.com/sweet-potato-gratin-with-smoked-gouda-and-rosemary-recipe/