Can I assemble the gratin without baking it?

Yes. The gratin can be assembled several hours in advance and kept in the refrigerator before baking. Just be aware that the potatoes may discolour slightly if left overnight before cooking.

Do I need a mandolin to make this recipe?

Not necessarily, but it makes it much easier to get even, very thin slices of potato. If using a knife, make sure it is sharp, and take your time to slice the potatoes evenly.

Can I freeze this potato and leek gratin?

Yes. Allow the gratin to cool completely, then wrap well and freeze for up to 3 months. Thaw overnight in the refrigerator before reheating in the oven until hot throughout.

Potato & Leek Gratin - Palate & Table

Ingredients

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20 grams butter, plus extra for greasing the baking dish
2 large leeks, trimmed, washed and thinly sliced
1.2 kilograms Agria potatoes, peeled and thinly sliced with a mandolin
16 grams fine sea salt
2 garlic cloves, halved
600 millilitres cream
200 millilitres whole milk
4 sprigs fresh thyme

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Instructions

Preheat the oven to 180°C (160°C fan bake).
Melt the butter in a saucepan over medium heat. Add the leeks, cover with a lid and cook for 5-8 minutes, stirring occasionally, until softened but not coloured.
Place the sliced potatoes and cooked leeks in a large bowl. Add the salt and toss well to combine.
Cut the garlic cloves in half and rub them all over the inside of a baking dish approximately 30cm x 20cm. Butter the dish, then transfer the potato and leek mixture to it, spreading it into an even layer.
Add the garlic cloves, cream, milk and thyme to a saucepan and gently heat over medium heat until just below a simmer. Strain the cream mixture over the potatoes and gently press them down so they are mostly submerged.
Cover the surface of the gratin with baking paper, followed by a layer of foil. This traps moisture and prevents the top from browning before the potatoes have had time to become tender. Bake for 1 hour 30 minutes. Remove the foil and baking paper and continue baking for 20-30 minutes, or until a knife slides easily through the potatoes and the top is golden brown. Rest for 10-15 minutes before serving.

Notes

The 16 grams of salt used in this recipe is approximately 1% of the combined weight of the potatoes and leeks. If you’re unsure of the total weight, it’s better to season a little more conservatively and add extra salt to taste after cooking.
Cooking times can vary depending on the thickness of your potato slices and the depth of your baking dish. The gratin is ready when a knife slides easily through the centre with very little resistance.
A mandolin isn’t essential, but it does make it easier to achieve evenly sliced potatoes, which helps the gratin cook more evenly.

Author: Ben Walls
Prep Time: 25 minutes
Resting Time: 15 minutes
Cook Time: 2 hours