Creamy Walnut & Herb Potato Gratin

There is something wonderfully comforting about a bubbling dish of potato gratin coming out of the oven. Thinly sliced potatoes become tender and velvety while the cream settles between every layer, creating a rich sauce that clings to each slice. This Creamy Walnut & Herb Potato Gratin takes that classic comfort food and gives it a deliciously rustic twist with toasted walnuts and fresh herbs.

The walnuts add a subtle crunch and a warm, nutty flavor that contrasts beautifully with the soft potatoes, while herbs bring freshness to the rich cream sauce. A golden, bubbling cheese topping finishes everything off and makes this dish equally suitable for a cozy family dinner or an elegant holiday table.

Why You’ll Love This Potato Gratin

This recipe is simple enough for a weeknight meal but impressive enough for entertaining. The ingredients are straightforward, yet the combination creates layers of flavor and texture.

The key is slicing the potatoes thinly and evenly. This allows them to cook at the same rate and absorb the creamy herb mixture as they bake. Toasting the walnuts before adding them to the dish also makes a big difference—their flavor becomes deeper and more aromatic.

Ingredients

For the Gratin

• 2 ½ pounds Yukon Gold or russet potatoes
• 1 cup heavy cream
• 1 cup whole milk
• 3 cloves garlic, finely minced
• 1 tablespoon fresh thyme leaves
• 1 tablespoon fresh rosemary, finely chopped
• 1 tablespoon fresh parsley, chopped
• 1 cup shredded Gruyère or sharp white cheddar cheese
• ½ cup finely chopped walnuts
• 2 tablespoons unsalted butter
• 1 teaspoon salt
• ½ teaspoon freshly ground black pepper
• ¼ teaspoon ground nutmeg

For the Topping

• ½ cup shredded Gruyère or cheddar
• ¼ cup chopped walnuts
• 1 tablespoon fresh parsley
• A few small thyme leaves, for garnish

Step 1: Prepare the Potatoes

Begin by washing and peeling the potatoes. If you prefer a more rustic gratin, you can leave the skins on, especially when using thin-skinned Yukon Gold potatoes.

Slice the potatoes into rounds approximately ⅛ inch thick. A mandoline slicer makes this especially easy, but a sharp knife works perfectly well.

Try to keep the slices as uniform as possible. If some slices are very thick while others are paper-thin, they will cook unevenly.

Once sliced, avoid soaking the potatoes in water. The natural starch on the surface helps the cream sauce thicken as the gratin bakes.

Step 2: Toast the Walnuts

Place a dry skillet over medium-low heat and add the chopped walnuts.

Toast them for approximately 3–5 minutes, stirring frequently. They should become fragrant and lightly golden but not dark or bitter.

Remove them from the heat immediately and transfer them to a plate to cool.

This small step gives the walnuts a much richer flavor and adds a pleasant roasted character to the finished gratin.

Step 3: Make the Creamy Herb Sauce

Preheat your oven to 375°F (190°C).

In a medium saucepan, combine the heavy cream and whole milk. Add the minced garlic, thyme, rosemary, salt, pepper, and nutmeg.

Warm the mixture over medium-low heat until it is hot and fragrant. Do not allow it to reach a vigorous boil. You simply want the herbs and garlic to gently infuse the dairy.

Remove the saucepan from the heat and stir in about 1 cup of shredded cheese.

Stir until the cheese melts into the warm cream, creating a smooth, flavorful sauce.

Taste the mixture and adjust the seasoning if necessary.

Step 4: Prepare the Baking Dish

Generously butter a 9-by-13-inch baking dish or a similarly sized gratin dish.

Use the butter to coat the bottom and sides. This prevents sticking while also adding another layer of richness to the potatoes.

For extra flavor, you can rub the inside of the dish with a halved garlic clove before buttering it.

Step 5: Build the Potato Layers

Arrange approximately one-third of the sliced potatoes across the bottom of the baking dish, slightly overlapping each slice.

Sprinkle a portion of the toasted walnuts and fresh parsley over the potatoes.

Pour some of the creamy herb sauce evenly over the layer.

Repeat the process:

Potatoes → walnuts and herbs → cream sauce

Continue layering until all of the potatoes have been used.

Finish with the remaining cream sauce, making sure it reaches down between the potato slices.

Gently press the layers down with the back of a spoon or spatula. This helps the cream distribute throughout the dish.

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