Wash a bowl so it is very cold, then dry.

Put the flour in the bowl, add three cubes of the butter and rub together so the mix resembles fine breadcrumbs.

Add the salt, then toss through the remaining cubes of butter.

Add 125ml iced water and the lemon juice, and bring the dough together into a scraggy mass.

Working on a floured board, shape the dough into a 10cm x 20cm rectangle and flour the top.

Use a floured rolling pin to roll out the rectangle to double its original size, then fold in both ends so they meet in the middle and fold again over the central divide, so the pastry now looks a bit like a book.

Rotate the book and repeat the process, extending, folding in the ends and turning the pastry back into a book.

Wrap and chill for an hour.

Meanwhile, working in a pan off the heat, beat the whole egg, egg yolks, sugar, cornflour and a few tablespoons of the warmed milk to make a thick paste.

Put the pan on a low heat and add the rest of the warmed milk, whisking constantly until the crema is thick.

Take off the heat, tip into a bowl and leave to cool.

Beat the cream until it’s thick, then chill.

Working on a floured surface, roll the dough into a 25cm x 20cm rectangle, then cut it into three even strips.

If possible, chill the strips, then arrange them side by side on a baking tray lined with greaseproof paper and prick all over.

Bake in a 180C (160C fan)/350F/gas 4 oven for 30 minutes, until golden, then remove and leave to cool completely.

Meanwhile, fold the whipped cream into the crema.

Put one of the pastry strips on a plate, then spread or pipe a layer of the cream mix on top.

Lay a second pastry strip on top, cover with of the cream mix, then top with the last strip of pastry and dust with icing sugar.