Cheesy Potato Gratin Thyme

There's something about a gratin that takes me back to my grandmother's kitchen on cold winter evenings. The first time I made this Cheesy Potato Gratin with Thyme, I wasn't trying to recreate her recipe—I was just craving that same warmth and comfort. What emerged from my oven was pure magic: layers of tender potatoes swimming in a silky cheese sauce, with fresh thyme whispering through every bite. It became the dish I reach for whenever I want to turn an ordinary dinner into something that feels like a celebration.

I remember the first time unexpected guests arrived for dinner and all I had planned was a simple salad. That's when I decided to make this gratin, layering the potatoes with determination and hope. When it came out of the oven with that golden, bubbling top, it became the star of the meal. My guests asked for the recipe before they even finished eating.

Ingredients

• Yukon Gold or Russet potatoes (1.5 kg, about 3.3 lbs), peeled and thinly sliced: Yukon Golds hold their shape beautifully and have that natural buttery quality that makes this dish sing. I always use a sharp knife or mandoline to get them thin enough—you want them delicate so they absorb all that cream without turning mushy
• Heavy cream (2 cups / 480 ml): This is where the luxury lives. Don't reach for light cream here; the fat is what creates that silky, luxurious sauce that coats every layer
• Whole milk (1 cup / 240 ml): Balances the richness of the cream and helps the sauce distribute evenly without becoming heavy
• Gruyère cheese (2 cups / 200 g), shredded: The backbone of this dish. Its nutty, slightly sweet flavor deepens as it bakes and creates those gorgeous golden spots
• Parmesan cheese (1 cup / 100 g), grated: This adds a sharper bite and helps the top get crispy and deeply golden. I always grate it fresh when possible
• Unsalted butter (2 tbsp / 30 g), plus extra for greasing: Use good butter here—it makes a difference in how the final dish tastes and how that topping browns
• Garlic (2 cloves), minced: Infuses the cream with just enough garlic presence to deepen the savory notes without overpowering the delicate potatoes
• Fresh thyme (2 tbsp leaves), plus extra for garnish: This herb is essential—it's what transforms this from 'cheesy potatoes' into something with real character and warmth
• Salt (1 tsp): Seasons the cream base properly from the start. The potatoes soak up this seasoning as they cook
• Freshly ground black pepper (1/2 tsp): Adds just enough bite to keep everything from tasting flat
• Freshly grated nutmeg (pinch), optional: This is the secret that makes people ask what spice they're tasting. Just a whisper changes everything

Instructions

Get Everything Ready:

Start by preheating your oven to 375°F (190°C). Take a 9x13-inch baking dish and butter it generously—this prevents the gratin from sticking and adds flavor at the edges. As your oven heats, peel and thinly slice your potatoes. I like to work quickly once they're cut so they don't oxidize and turn gray, but honestly, a little discoloration won't affect the final dish.

Make the Cream Base:

In a saucepan over medium heat, combine your heavy cream, whole milk, minced garlic, fresh thyme, salt, pepper, and that optional nutmeg. This is where the magic starts. Listen for the moment it begins to steam gently—you're not boiling it, just warming it enough to let the flavors infuse and bloom. The smell that rises from that pan is already telling you this will be special.

Layer Your Foundation:

Spread half your sliced potatoes evenly across the bottom of the prepared dish. They should cover the bottom in a relatively even layer. Don't worry about perfection—gaps actually let the cream seep through and keep everything moist. Over those potatoes, sprinkle half of your shredded Gruyère and grated Parmesan. The cheese will nestle between the potato slices and create pockets of melted richness.

Add the First Cream Wave:

Carefully pour half of that warm cream mixture over the potatoes and cheese. Watch as it soaks into the layers, bringing all that garlic and thyme flavor deep into the dish. You'll see the liquid level rise, and that's perfect—this is a creamy dish, not a dry one.

Build to the Top:

Layer the remaining potato slices over the cream, building toward the top of the dish. This is the second potato layer, and it becomes your canvas. Top it with the rest of your cheeses, spreading them evenly. This top layer will brown and crisp up beautifully in the oven, creating texture against the creamy middle.

The Final Cream Pour:

Pour the remaining cream mixture evenly over the top layer. The liquid should come up to about three-quarters of the way up the potatoes—you want them mostly submerged but not drowning. Now dot the top with small pieces of unsalted butter. These little pats will melt and contribute to that golden crust that forms.

The Covered Bake:

Cover your dish tightly with foil and slide it into the preheated oven. This initial 40 minutes of covered baking is crucial—it allows the potatoes to steam in the cream and become tender while the moisture stays trapped. You can walk away during this time and prepare the rest of your meal.

The Golden Finish:

After 40 minutes, carefully remove the foil. The kitchen will smell incredible. What you're looking for now is browning and bubbling around the edges. Slide it back into the oven uncovered for another 20 minutes. You're waiting for the top to turn golden brown and for you to see the cream bubbling gently at the edges. This is how you know the potatoes are fork-tender and everything is heated through.

Rest and Garnish:

When it's done, remove the gratin and let it rest for 10 minutes. This resting period lets everything set slightly so it doesn't fall apart when you serve it. Scatter extra fresh thyme leaves over the top—they add a fresh note and beautiful green color to all that golden-brown richness.

Save

This dish has become my answer whenever someone asks me to bring something to a winter gathering. There's something about watching people's faces light up when they taste that first creamy, cheesy, thyme-perfumed bite—it reminds me why I love cooking. It's not just food; it's comfort that you can share.

Keeping It Fresh and Tasting Perfect

This gratin is best served fresh from the oven while the cheese is still melting and the potatoes are at their most tender. However, it reheats beautifully. You can make it a few hours ahead and reheat it gently in a 325°F oven, covered with foil, for about 15 minutes until it's warmed through. The flavors actually deepen after a day in the refrigerator, making this a wonderful dish to prepare ahead for holiday dinners or special occasions.

When You're Missing Something

If you find yourself without Gruyère, sharp cheddar brings a different but equally delicious sharpness, while Emmental works beautifully if you want something milder. Some cooks swear by adding a layer of sautéed onions between the potatoes and cheese—if you go this route, cook them down until they're caramelized and sweet so they meld into the dish rather than overpowering it. A few paper-thin slices of truffle, if you're feeling luxurious, can transform this from special occasion dish into something truly memorable.

Serving Ideas That Clicked

This gratin shines alongside roasted meats, from a simple roasted chicken to beef tenderloin. It's elegant enough for holiday tables but comforting enough for weeknight dinners. A crisp white wine like Sauvignon Blanc or a light Pinot Grigio pairs beautifully with all that creamy richness. For a lighter meal, serve it with a simple green salad dressed with a bright vinaigrette to cut through the richness. At Christmas dinner, it takes the place of heavier starches and lets the main proteins shine while still providing that sense of abundance.

• Make sure to let guests know it's best served while still warm, though room temperature leftovers are surprisingly good
• If you're feeding a crowd, this recipe doubles easily in a larger baking dish or two standard ones
• Leftovers keep for three to four days in the refrigerator and can be reheated gently in the oven until warmed through

Save

This gratin is the kind of dish that reminds you why cooking for people you care about matters. Make it once, and it becomes a go-to recipe you'll return to again and again.

Questions & Answers

→ What type of potatoes work best?

Yukon Gold or Russet potatoes are ideal due to their texture and ability to absorb flavors while maintaining firmness after baking.

→ Can I substitute the cheeses used?

Gruyère can be replaced with sharp cheddar or Emmental for a different but still flavorful result.

→ How does fresh thyme enhance the dish?

Fresh thyme adds a subtle herbal fragrance that complements the rich cream and melted cheeses, balancing the dish's richness.

→ What is the best way to slice potatoes for even cooking?

Using a sharp chef's knife or mandoline ensures uniform thin slices, promoting even baking and consistent texture.

→ Any tips for achieving a golden top layer?

Baking uncovered for the last 20 minutes allows the cheese topping to brown and develop a crisp, appealing crust.