Name: Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe
Prep time: 20 min
Cook time: 55 min
Total time: 1 h 15 min
Cuisine: French
Ingredients: 1 ½ pounds red-skinned sweet potatoes; 1 pound Yukon Gold potatoes; 1 ½ cups half-and-half; 1 ½ tablespoons butter (divided); 1 ½ cups shredded Gruyère cheese; ¼ cup finely shredded Parmesan cheese; 1 teaspoon minced garlic; 1 tablespoon chopped fresh thyme; ½ teaspoon fine ground sea salt (or to taste); Freshly ground black pepper (to taste)

Jump to Recipe· 4.3 from 2 reviews

There is something truly magical about the Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe that makes it an irresistible go-to for any occasion. This dish layers creamy, tender sweet potatoes and Yukon Gold potatoes with the rich, nutty flavors of Gruyère and sharp Parmesan cheeses, all baked to a golden, bubbly perfection. It’s comforting yet elegant, boasting a beautiful mix of colors, textures, and tastes that will have everyone swooning. Whether you’re making it for a family dinner or a special celebration, this gratin delivers warmth and indulgence in every bite.

Ingredients You'll Need

A shiny metal pot filled with a creamy white sauce that has small lumps floating in it, placed on a white marbled surface. Around the pot, there are several small white bowls: one filled with thinly sliced orange and yellow sweet potatoes on the left side, another filled with shredded cheese at the top, a bowl with green herbs slightly to the right, and a small bowl with black pepper at the bottom left. The arrangement is neat, with clean colors and soft natural light. photo taken with an iphone --ar 4:5 --v 7

The beauty of this Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe lies in its simple, quality ingredients that come together to create layers of flavor and luscious texture. Each element plays a crucial role, from the creamy half-and-half that gently cooks the potatoes, to the fresh thyme that adds an herbaceous touch. Here’s what you’ll want to gather before starting:

Red-skinned sweet potatoes (1 ½ pounds): Adds natural sweetness and vibrant orange color to the gratin.
Yukon Gold potatoes (1 pound): Provides creamy texture and neutral balance to the sweet potatoes.
Half-and-half (1 ½ cups): Creates the luscious, velvety sauce that binds the layers together.
Butter (1 ½ tablespoons, divided): Used for richness and to prevent sticking in the baking dish.
Minced garlic (1 teaspoon): Adds a subtle fragrant depth to the creamy sauce.
Fresh thyme (1 tablespoon, chopped): Gives a bright, earthy note that complements the potatoes perfectly.
Fine ground sea salt (½ teaspoon): Enhances all the flavors without overpowering them.
Freshly ground black pepper (to taste): Adds mild warmth and a little bite.
Gruyère cheese (1 ½ cups shredded): Melts beautifully and adds a nutty, slightly sweet character.
Parmesan cheese (¼ cup finely shredded): Gives an extra punch of sharp, savory umami on top.

How to Make Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe

Step 1: Prepare the Potatoes

Start by peeling your sweet potatoes and Yukon Gold potatoes. Using a mandoline slicer or the slicing blade of a food processor, cut them into thin, uniform ⅛-inch rounds. This thickness allows the layers to cook evenly while maintaining some tender bite. The contrast between the orange sweet potato and the pale Yukon Gold adds visual interest even before baking.

Step 2: Make the Creamy Sauce

In a small saucepan, combine the half-and-half, 1 tablespoon of butter, and minced garlic. Warm this mixture over low heat, stirring occasionally so the flavors meld without boiling. This mixture will become your silky sauce to soak into the potato layers, infusing them with subtle garlic richness.

Step 3: Prepare Your Baking Dish

Preheat your oven to 400 degrees F. While it heats, use the remaining ½ tablespoon of butter to generously butter a 12-inch cast iron pan or similar gratin dish. This step is key to ensuring the gratin doesn’t stick and helps develop that irresistible crust at the edges.

Step 4: Layer the Potatoes and Seasonings

Begin your gratin by spreading half of your potato slices in the baking dish, alternating between sweet potato and Yukon Gold slices. This layering creates the signature mix of flavors and colors. Sprinkle half of your salt, freshly ground black pepper, and chopped thyme evenly over this layer, then add half of the shredded Gruyère and Parmesan to distribute the cheesy goodness throughout.

Step 5: Repeat and Press Down

Repeat the layering with the remaining potatoes, salt, pepper, thyme, and cheeses, pressing down gently with your hands to compact everything firmly together. This helps the layers meld during baking and ensures even cooking. Once packed, pour the warm half-and-half and garlic sauce over the top, letting it seep between the layers.

Step 6: Bake to Golden Perfection

Cover the gratin and bake for 40 minutes, allowing the potatoes to soften in the creamy sauce. Then, remove the cover and bake for an additional 15 minutes. This finale crisps up the golden top and lets excess liquid evaporate, giving you that irresistible cheesy crust. Once out of the oven, let it rest for 5 to 10 minutes before serving to set everything beautifully.

How to Serve Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe

The dish shows thinly sliced layers of orange and pale yellow root vegetables, likely sweet potatoes and regular potatoes, arranged closely in a round white pan. The top layer has a slightly browned and bubbly cheese coating with small green herb sprigs scattered for garnish. The arrangement of the round vegetable slices creates a spiral pattern, and the texture looks soft and creamy with some crispy edges. A golden spoon lifts a portion revealing the layered stack inside, showing the soft, moist texture of the baked vegetables. The background is a white marbled surface with soft natural light. Photo taken with an iphone --ar 4:5 --v 7

Garnishes

Add flair and freshness to your gratin with a sprinkle of finely chopped fresh thyme or rosemary just before serving. A light dusting of extra Parmesan on top can create a subtle crisp, or a few twists of fresh black pepper will amplify the cozy flavors. These simple garnishes make the dish feel even more special at the table.

Side Dishes

This gratin pairs wonderfully with protein-rich dishes like roast chicken, pork tenderloin, or a juicy steak. For a vegetarian meal, serve alongside roasted seasonal vegetables or a bright green salad with lemon vinaigrette to balance the richness. Its creamy texture and inviting flavors make it flexible enough to complement many mains.

Creative Ways to Present

For a stunning presentation at a holiday dinner or potluck, serve the gratin in individual ramekins or small cast iron skillets. Layer it in a clear glass baking dish to showcase those beautiful potato colors on display. You can also add a pop of color by topping with finely chopped chives or crispy fried shallots for crunch and visual appeal.

Make Ahead and Storage

Storing Leftovers

Leftover gratin keeps beautifully in an airtight container in the refrigerator for up to 3 days. The flavors actually deepen overnight, making it a perfect make-ahead dish. Just be sure to store it once completely cooled to preserve texture and freshness.

Freezing

This gratin freezes well if stored properly. Wrap it tightly with plastic wrap and aluminum foil to prevent freezer burn, then freeze for up to 2 months. When ready to enjoy, thaw overnight in the fridge before reheating to maintain the creamy texture without drying out.

Reheating

Reheat leftover or thawed gratin covered with foil in a 350-degree F oven until warmed through, about 20–25 minutes. For a crispier top, remove the foil during the last 5 minutes. Avoid microwaving if possible, to keep the layers intact and creamy.

FAQs

Can I use other types of cheese in this gratin?

Absolutely! While Gruyère and Parmesan are traditional for their meltability and sharp, nutty flavors, you can experiment with cheeses like Fontina, Emmental, or even a bit of sharp cheddar, depending on your taste. Just keep the cheese balance to avoid overpowering the potatoes.

Why use both sweet potatoes and Yukon Gold potatoes?

The combination offers a delightful contrast—sweet potatoes add natural sweetness and vibrant color while Yukon Gold provide a creamy, buttery texture. Together, they create a perfect harmony of flavor and texture that a single potato variety can’t achieve alone.

Can I make this dish vegan or dairy-free?

This recipe relies on dairy for richness but can be adapted. Use plant-based half-and-half, vegan butter, and dairy-free cheese alternatives. Keep in mind that the flavor and texture will change, but it can still be delicious with the right substitutes.

Is it necessary to slice the potatoes so thin?

Yes, thin slices are essential for even cooking and melding the layers together. Thicker slices might not cook through evenly and could leave the gratin uneven in texture. A mandoline slicer makes this quick and easy.

Can I prepare the gratin the day before baking?

Definitely! Assemble the gratin, cover, and refrigerate overnight. When ready to bake, let it come closer to room temperature first and then bake as directed. This is a great time-saving tip for busy days or holiday meals.

Final Thoughts

This Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe is a true labor of love that rewards you with layers of creamy, cheesy comfort and vibrant flavor. It's one of those dishes that feels special enough for any celebration but simple enough to enjoy any night of the week. I can’t recommend it enough—once you try this gratin, it’s guaranteed to become a treasured favorite in your recipe box!

Sweet Potato and Yukon Gold Potato Gratin with Gruyère and Parmesan Recipe

Ingredients You'll Need