Prep 40 min
Chill/rest 1 hr
Cook 30 min
Serves 6
For the pastry
225g plain flour
2 tbsp caster sugar
½ tsp salt
120g cold butter
1 egg yolk
2 tbsp cold water
3 digestive biscuits
For the filling
6 lemons, at least 3 of them unwaxed for preference
25g cornflour
175g caster sugar
3 egg yolks
25g butter
For the meringue
4 egg whites
1 pinch of salt
225g caster sugar
2 tsp cornflour
1 Make the pastry dough
Start with the pastry. LMP requires a sturdy, rich shortcrust, which you’ll need to make yourself (you could use a ready-made sweet shortcrust, if you prefer, but this is much nicer). Mix the flour, sugar and salt in a large bowl, grate in the butter, then rub it in using your fingertips. Alternatively, pulse everything in a food processor to coarse crumbs.
2 Finish the pastry …
Add the egg yolk and just enough of the cold water (you shouldn’t need it all) that it comes together into a soft, but not sticky dough that you’re able to shape into a coherent ball – too much water will cause the pastry to shrink in the oven, while too little will mean it’ll disintegrate under the rolling pin, so add it gradually.
3 … then chill and rest
Flatten the pastry ball, then wrap and chill for 30 minutes (if you need to leave it in the fridge for longer, get it out a little while before you want to roll it out).
Meanwhile, grease a 20-22cm loose-bottomed tart tin, and crush the digestives to crumbs (putting them in a bag and whacking them with a rolling pin is a fun way to do this).
4 Roll out the pastry
Scatter half the biscuit crumbs on a work surface, then lay the pastry on top and roll out to about 5mm thick. Scatter the remaining crumbs on top, then use the pastry to line the tin, trimming it neatly, so there’s still just a little standing proud of the sides. Chill for another 30 minutes. Heat the oven to 200C (180C fan)/390F/gas 6.
5 Blind bake the pie case
Prick the base all over with a fork, then line the tin with greaseproof paper and baking beans or similar (dried beans, rice, etc) and bake for 20 minutes. Carefully lift out the beans and paper, bake the base for another five to seven minutes, until the pastry is dry and pale golden, then remove and leave to cool.
6 Start on the lemon filling
Zest three of the lemons (if they’re waxed, scrub the skin well with hot water first), then juice all six of them: you should end up with about 200ml.
Put both the zest and the juice in a saucepan. Whisk 50ml water into the cornflour until smooth, then whisk this into the pan. Stir in the sugar and egg yolks.
7 Pour into the tart case
Dice the butter and put it near the hob. Put the pan on a low flame and heat gently, stirring, until the mix is warm. Still stirring, add the butter, then slowly bring the mixture up to a simmer. Once the lemon thickens and reaches the consistency of thick custard, spoon it into the tart case and set aside to cool completely (it will continue to firm up as it cools).
8 Make the meringue
Heat the oven back up to 200C (180C fan)/390F/gas 6. In a large clean bowl, or in a food mixer, whisk the egg whites and a pinch of salt to soft peaks.
Whisk in the sugar a spoonful at a time, then carry on whisking until the meringue mix is stiff and shiny. Finally, whisk in the cornflour.
9 Finish the pie
Spoon the meringue on top of the pie, artistically shaping it into snowy peaks. Bake for about 15 minutes, until the meringue is lightly golden on top. Leave to cool before serving. The soft meringue means that this is not a dessert that keeps particularly well, but cover any leftovers loosely with foil and refrigerate.
