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1
Make & Chill the Pastry
15 Mins + 20 Mins Chill
Cold butter, about 4°C (40°F)
Rub the cold diced butter into the flour and 2 g of salt until the mix looks like fine breadcrumbs. Add the beaten egg and just enough cold water to bring it together into a smooth dough. Flatten into a disc, wrap and chill for 20 minutes.
Stop rubbing as soon as the crumbs form — overworked pastry turns tough, not crisp.
Done when: A smooth, firm disc that holds together without cracking.
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2
Roll Out & Blind Bake
15 Mins
180°C (350°F)
Roll the pastry out on a floured surface and line a 26 cm tart tin, trimming the edges. Prick the base with a fork, line with baking paper and fill with baking beans, then blind bake for 15 minutes until the base looks dry and pale.
Blind baking is what keeps the bottom crisp under a moist leek filling.
Done when: A dry, pale, set pastry shell with no wet spots.
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3
Sweat the Leeks
12 Mins
Medium heat, about 160°C (320°F)
Melt the 30 g of butter in a wide pan, add the sliced leeks with a pinch of salt, cover and cook gently for 10–12 minutes until completely soft and sweet, stirring now and then. Do not let them brown.
Soft leeks, never browned, give the tart its gentle sweetness — browning turns them bitter.
Done when: Leeks wilted, glossy and sweet-smelling, with no colour.
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4
Whisk the Custard
5 Mins
Room temperature, about 20°C (68°F)
Whisk the 3 eggs with the cream, nutmeg, pepper and the remaining 3 g of salt. Stir in the cooled leeks and half the grated Gruyère.
Let the leeks cool for 5 minutes first — hot leeks would scramble the eggs.
Done when: A thick, creamy mix with leeks evenly distributed through it.
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5
Fill & Bake the Tart
35 Mins
190°C (375°F)
Pour the leek mixture into the blind-baked shell, level it gently and scatter the remaining Gruyère over the top. Bake for 30–35 minutes until the filling is set, the top is golden and the pastry edge is crisp.
The tart is done when the centre barely trembles — it firms up as it cools.
Done when: Golden top, set centre, and a pastry edge that sounds crisp when tapped.
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6
Rest & Serve
10 Mins
Room temperature, about 20°C (68°F)
Leave the tart in its tin for 10 minutes before slicing, so the filling sets and the slices hold their shape. Serve warm, in wedges, with a green salad.
Cutting too soon is the classic mistake — the filling runs and the slice collapses.
Done when: Clean wedges that hold their shape, with a creamy leek centre.
auto_awesome Finishing Touches & Plating
Serve warm with a lightly dressed green salad and a spoonful of Dijon mustard on the side. The tart is also good at room temperature the next day, which makes it a fine picnic dish.
Belgium
1h
