Equipment
* optional
Ingredients
Produce
- 1000 g starchy potatoes, peeled
- 2 garlic, minced
Dairy & Eggs
- 500 ml whole milk, room temperature
- 2 large eggs, beaten
- 150 g gruyère cheese, freshly grated
- 30 g unsalted butter, softened
Seasonings
- 10 g fine sea salt
- 2 g black pepper, freshly cracked
- 1 g ground nutmeg
Nutrition (per serving)
Method
Preheat the oven to 190°C/375°F.
Rub the inside of a 2-liter baking dish with 10g of the softened butter, then rub the buttered surface with a small pinch of the minced garlic to season the dish.
Slice the peeled potatoes to a uniform 2-3mm thickness using a mandoline slicer or sharp knife. Do not rinse the slices, as the surface starch is essential for thickening the gratin.
In a large mixing bowl, thoroughly whisk together the whole milk, eggs, remaining minced garlic, salt, black pepper, and nutmeg.
Arrange half of the potato slices in the prepared baking dish in overlapping layers. Pour half of the milk and egg mixture over the potatoes and sprinkle with evenly with half of the grated gruyère. Repeat with the remaining potatoes, milk mixture, and cheese. Dot the surface with the remaining 20g of butter.
Bake uncovered at 190°C/375°F for 60 minutes. The gratin is done when the potatoes offer no resistance to a knife and the cheese has formed a deep golden, bubbling crust.
Remove the baking dish from the oven and let the gratin rest at room temperature for 15 minutes before serving. This allows the custard to set properly for clean slicing.
Chef's Notes
- Never rinse the potatoes after slicing them. The natural starches released during slicing are necessary to bind with the milk and eggs, creating the luxurious, cohesive texture of the gratin.
- Nutmeg is a classic pairing with both potatoes and dairy in French cooking. Always use freshly grated whole nutmeg if possible, as pre-ground nutmeg loses its volatile oils quickly.
- If you notice the top browning too quickly during the last 20 minutes of baking, tent the dish loosely with aluminum foil to protect the cheese while the potatoes finish cooking.
Storage
Refrigerator: 4 days — Store in an airtight container.
Freezer: 1 month — Freezing may slightly alter the texture of the potatoes, but it remains delicious.
Reheating: Reheat in a 175°C/350°F oven covered with foil for 20 minutes, or until warmed through.
