Break up the biscuits into halves by hand and then pulse in a food processor until they reach the crumb stage. Alternatively, put them in a ziplock bag and crush with a rolling pin. Transfer to a bowl.

Melt the butter in a saucepan or in the microwave and mix with the crumbs.

Divide the mixture between the six ramekins and press down in an even layer using the back of a spoon.

Put the ramekins in the freezer while you make the custard.

Zest the lemons.

Preheat the oven to 150 C / 300 F / 130 FAN / Gas 2.

Separate the eggs and place the yolks in a mixing bowl with 50g of the sugar.

Whisk for 2 minutes until the mixture is pale and frothy.

Put the cream in the saucepan over a low to medium heat. Bring to simmer then remove and leave to cool for 10 minutes.

Whisk in a small amount of cream into the egg yolks then gradually pour in the rest, whisking all the time.

Stir in the lemon zest and check the taste. Add more lemon zest if necessary.

Put the dishes into the roasting tins and pour hot tap water into the base to come halfway up the dishes.

Divide the custard mixture between the dishes.

Bake ramekins for an hour, or until the custard is just set.

Remove from the water bath, leave to cool then refrigerate for an hour.

Sprinkle the top of the custard with the remaining sugar and use a blow torch to melt and caramelise.

Allow to sugar to harden for a few minutes before serving.