In a mixing bowl add the butter to the flour and lightly rub in with your fingers until the mixture resembles breadcrumbs.
Add the cold water and with a blunt knife, gently bring the pastry together, then finish off with your hands, trying to work the dough as little as possible.
You may need to add a drop or two more water if there are still a lot of crumbs of flour.
Once the dough is just combined, wrap in clingwrap and place in fridge for at least half an hour. (You can make the pastry up to 2 days before you want to cook the quiche, or freeze for up to a month).
Preheat the oven to 190˚C/370˚F
Roll out the pastry on a gently floured work surface. Sprinkle the top with flour and roll out the pastry to a 27cm diameter circle.
Gently roll the pastry so it wraps around the rolling pin then lift this over to your dish. Unroll it over your 23cm/9” pie tin/dish.
Trim the edges. If there are any tears in the pastry, dab a little water around the edges of the hole, and then press a pastry scrap into the hole.
Prick the base lightly with a fork then line it with a large piece of baking paper and fill with some rice or cooking beans. Place in oven for 15 minutes.
Remove the baking beans and baking paper (taking care as the beans/rice will be very hot) then, using a pastry brush, brush a little of the beaten egg all over the pastry. Return to the oven and bake for 5-7 minutes, until golden.
Turn the oven down to 170˚C/ 340˚F.