Process flour, butter, and icing sugar and butter until the mixture is well combined. It will start to clump together and look like breadcrumbs.
Add water and egg yolk and mix until dough forms. Add more water if it’s a little dry.
Knead dough on a floured board until smooth.
Make a ball out of the pastry, wrap with cling wrap and refrigerate for at least a ½ hour until thoroughly chilled.
Preheat oven to 180°C (fan-forced) and grease a 24cm fluted tin.
Roll pastry until about 5mm thick and line the bottom and sides of the tin. Cut excess from the top using a knife then refrigerate for another ½ hour.
Line pastry with baking paper and fill with pie weights. If you don’t have weights you can use rice which also works well.
Bake for 12-15 minutes then remove the weights and paper. Continue baking until golden in colour (about 5 minutes).
Set pastry aside to cool and reduce oven temperature to 140°C (fan-forced).
To make filling beat egg yolks, caster sugar, and eggs. Gently fold in chocolate and cream until combined.
Pour filling into the pastry case and bake for 25 to 30 minutes or until just set.
Refrigerate until chilled then serve with vanilla ice cream.