Creamy Potato and Leek Gratin
- Savory
- Comforting
- Oven
Thin potato slices layered with softened leeks and garlic, bathed in nutmeg-scented cream and topped with golden Gruyère. A hearty oven-baked gratin with a bubbling, browned crust.
- Total
- 1 h 38
- Prep 20 · Cook 68 · Rest 10
- Serves
- 4
- Difficulty
- Easy
You'll practice: Sweating · Seasoning in layers
Instructions
-
Heat the oven to 180°C. Peel the potatoes and slice them 3 mm thick. Cut the leeks in half lengthways, slice them 1 cm thick, and wash well. Mince the garlic. Grate the gruyere.
~15 min
-
Toss the leek slices with the olive oil in the baking dish and spread them in an even layer. Bake for 12 minutes, until softened and lightly golden at the edges.
~12 min
Baking the leeks first softens them and drives off water, so they turn sweet and silky instead of releasing liquid into the cream.
Sweating Bake the leeks gently until soft and translucent, not browned hard; this coaxes out sweetness and keeps them from turning bitter.
-
While step 2 cooks
While the leeks bake, whisk the 300 ml cream with the garlic, nutmeg, 1 tsp of the salt and the black pepper in a bowl.
~3 min
Whisking dissolves the salt and disperses the garlic and nutmeg evenly, so every layer of potato gets the same seasoned cream.
-
Take the dish from the oven and scatter the softened leeks into the bowl with the 300 ml cream. Layer half the potato slices in the dish, season with the remaining 0.5 tsp salt, then add the leek-cream mixture and the rest of the potatoes in overlapping layers. Pour over any cream left in the bowl.
~8 min
Overlapping the slices and salting between layers builds even seasoning and lets the cream seep into the gaps, giving a cohesive, sliceable gratin.
Seasoning in layers Salt each potato layer as you build it rather than only on top, so the seasoning reaches every slice evenly.
-
Cover the dish tightly with foil and bake for 40 minutes, until the potatoes are tender when pierced with a knife.
~40 min
The foil traps steam, which cooks the potatoes through gently before the top dries out or the cheese browns too early.
-
Remove the foil, scatter the gruyere over the top and bake uncovered for 13 minutes, until the cheese is melted and browned and the cream bubbles at the edges.
~13 min
Uncovering lets moisture escape and the surface reach browning temperature, melting the cheese and thickening the cream into a glossy sauce.
For a deeper golden top, switch to the oven's grill setting for the last 2 to 3 minutes of the uncovered bake, watching closely so the gruyere browns without burning.
-
Let the gratin stand for 10 minutes before serving so the layers set and the cream thickens.
~10 min
Resting lets the hot cream cool and thicken slightly, so the layers hold together and the portions cut cleanly instead of running.
