Sweet Potato Gratin with Gouda, Thyme, and Parmesan Recipe
This Sweet Potato Gratin is a comforting fall and winter side dish featuring layers of thinly sliced sweet potatoes baked with a rich combination of Gouda, Parmesan cheese, fresh thyme, cream, and milk. The result is a creamy, cheesy casserole with a golden browned top and tender, flavorful layers—perfect for holiday dinners or cozy family meals.
- Prep Time: 15 minutes
- Cook Time: 1 hour 15 minutes
- Total Time: 1 hour 30 minutes
- Yield: 6 servings
- Category: Side Dish
- Method: Baking
- Cuisine: American
Ingredients
Sweet Potato Layer
- 3 large sweet potatoes, peeled and sliced ⅛ inch thick (about 2 pounds)
- Kosher salt, to taste
- Freshly ground black pepper, to taste
- 1 teaspoon fresh thyme, roughly chopped
Cheese and Cream Mixture
- ½ cup Parmesan cheese, shredded
- 1 ½ cups shredded Gouda cheese
- ¾ cup milk
- ¾ cup heavy cream
Instructions
- Preheat and Prep: Preheat the oven to 400°F (200°C). Lightly grease a cast iron skillet to prevent sticking and to ensure even browning.
- Mix Cream and Milk: In a bowl, combine the heavy cream and milk. Set this mixture aside for layering.
- Assemble Layers: Begin arranging the sweet potato slices evenly in the skillet, creating a single layer. Drizzle a few tablespoons of the cream and milk mixture over the potatoes, then season with kosher salt, freshly ground black pepper, and some of the chopped thyme. Sprinkle with a portion of the Parmesan and Gouda cheeses. Repeat this layering process—potatoes, cream mixture, seasonings, and cheese—until you have 6 to 8 layers, pressing down gently so the sweet potatoes are fully submerged in the cream mixture. Top with additional cheese if desired.
- Bake Covered: Cover the skillet with a lid or foil and bake in the preheated oven for 30 minutes. This initial bake helps the potatoes start to soften and the flavors blend.
- Bake Uncovered and Brown: Remove the cover and continue baking for an additional 30 to 45 minutes. Bake until the cream is mostly absorbed, the sweet potatoes are tender through to the center, and the top is nicely browned and bubbly.
- Rest and Serve: Remove the gratin from the oven and let it rest for 15 minutes to set before serving. This resting period ensures that the dish holds together when sliced and enhances the flavors.
Notes
- To prepare ahead, assemble the gratin and bake covered for 30 minutes (par-baking). Let cool to room temperature, cover, and refrigerate overnight.
- The next day, bake uncovered for the remaining 30 to 45 minutes until heated through and browned.
- Use a mandoline for perfectly thin and even sweet potato slices for uniform cooking.
- For a milder flavor, you can substitute Gouda with Gruyère or a similar melting cheese.
- Cast iron skillet is preferred for even heat distribution and a nicely browned crust, but a baking dish will work as well.