Creamy French Pommes Dauphinoise with Gruyère Crust Step-by-step instructions

Before you start

Before starting, set out all ingredients and equipment. Peel and slice the potatoes just before assembling to prevent browning; keep them in a bowl of cold water if needed, then pat dry. Grate the Gruyère cheese fresh from the block for the best melt.

Butter the baking dish generously. Preheat the oven to 350°F (175°C). Have the cream, milk, garlic, bay leaf, and nutmeg measured and ready. The cream infusion takes about 10 minutes, so begin that first while preparing the potatoes.

Instructions

Infuse and Slice

1. 1Infuse the cream
   In a medium saucepan, combine the heavy cream, whole milk, smashed garlic cloves, bay leaf, and freshly grated nutmeg. Place over medium heat and bring to a gentle simmer, stirring occasionally. Once small bubbles appear around the edges, remove from heat and let steep for 10 minutes. Discard the bay leaf and garlic cloves.
   Look for The cream is steaming and fragrant with garlic and nutmeg, with tiny bubbles at the edges.
   Tip Do not let the cream boil rapidly; a gentle simmer prevents scorching and keeps the dairy smooth.
2. 2Slice the potatoes
   While the cream steeps, peel the Yukon Gold potatoes and slice them into 2 mm thick rounds using a mandoline. Keep the slices in a bowl of cold water to prevent browning, then drain and pat dry thoroughly before layering.
   Look for Potato slices are paper-thin and uniform, about the thickness of a coin.
   Tip A mandoline ensures even slices; if using a knife, aim for consistent thinness for even cooking.
3. 3Butter the dish
   Preheat the oven to 350°F (175°C). Generously rub the inside of a ceramic baking dish with the butter, covering the bottom and sides completely.
   Look for The dish glistens with an even coating of butter.
   Tip Buttering prevents sticking and adds a subtle richness to the edges.

The cream is gently simmering with garlic, bay leaf, and nutmeg, releasing a warm, aromatic scent. The potatoes are sliced into thin, even rounds, ready to be layered. The buttered dish awaits, and the oven is preheated. This phase is about preparation and precision—take your time to ensure the slices are uniform and the cream is well infused. The kitchen should smell invitingly of garlic and spice, setting the stage for the rich layers to come.

Layer and Bake

4. 4Layer the potatoes
   Arrange one-third of the potato slices in the buttered dish, overlapping them slightly in concentric circles. Sprinkle with one-third of the grated Gruyère. Repeat with two more layers, finishing with a layer of cheese on top.
   Look for Potatoes and cheese are stacked in even, neat layers.
   Tip Overlap the potatoes like shingles for a cohesive gratin that holds together when sliced.
5. 5Pour the cream
   Pour the infused cream mixture evenly over the layered potatoes, allowing it to seep between the slices. Gently press down with a spatula to ensure the top layer is moistened.
   Look for The cream rises between the potato layers, coating them evenly.
   Tip Do not overfill; the cream should come just to the top without overflowing.
6. 6Bake covered
   Cover the dish tightly with aluminum foil and place it on a baking sheet to catch any drips. Bake for 45 minutes, or until the potatoes are nearly tender when pierced with a knife.
   Look for The cream is bubbling gently around the edges and the potatoes yield slightly to a knife.
   Tip Baking covered traps steam and ensures the potatoes cook through without drying out.

The potatoes and cheese are stacked in neat layers, and the cream is poured over, seeping into every crevice. As the dish bakes, the cream bubbles gently around the edges, and the aroma of garlic and nutmeg fills the kitchen.

The potatoes are becoming tender, absorbing the creamy liquid. After 45 minutes, the gratin should be nearly set, with the top just beginning to brown. Check that a knife pierces the potatoes with little resistance before moving to the broiler.

Broil and Rest

7. 7Broil the top
   Remove the foil and increase the oven temperature to broil. Place the dish under the broiler for 3 minutes, watching closely, until the Gruyère is blistered and deep golden brown in spots.
   Look for The cheese is bubbling, blistered, and mahogany in patches.
   Tip Watch constantly to prevent burning; broilers vary in intensity.
8. 8Rest and garnish
   Remove the gratin from the oven and let it rest for 10 minutes. Scatter fresh thyme leaves over the top just before serving.
   Look for The gratin is set and slightly puffed; the thyme adds a fresh green contrast.
   Tip Resting allows the layers to set, making clean slices easier.

Under the broiler, the Gruyère sizzles and blisters, turning deep mahogany in spots. The top is crisp and golden, while the interior remains creamy and hot. After removing from the oven, the gratin rests, allowing the layers to set. The final dish is a stunning contrast of textures: a crackling cheese crust over silky, tender potatoes. Garnished with thyme, it is ready to serve, holding its shape beautifully on the plate.

Common mistakes

One common mistake is slicing the potatoes too thick, which leads to uneven cooking and a crunchy texture. Use a mandoline for consistent 2 mm slices. Another issue is overfilling the dish with cream—the potatoes should be just covered, not swimming.

If the top browns too quickly during baking, cover with foil and continue cooking. Skipping the rest period can cause the gratin to fall apart when served; let it set for at least 10 minutes. Also, avoid using pre-shredded cheese, as it may not melt as smoothly.

How to tell it’s done

The gratin is done when the potatoes are completely tender and a knife slides through the layers with no resistance. The top should be deep golden brown and blistered in spots from the broiler, with the cheese bubbling and slightly caramelized.

After resting, the gratin should hold its shape when sliced, with the cream thickened to a velvety sauce that clings to the potatoes. If the potatoes are still firm in the center, return the dish to the oven (covered) for 5-10 more minutes before broiling.