Coat the inside of your pie dish with a teaspoon of butter. I used my fingers to do this, making sure to get a thin, even coating of butter all over the inside of the dish. This stops the pastry from sticking to the dish as it bakes.
Now use your fingers to press your chilled dough into the pie dish in an even layer about 1/3-inch thick. You want the pastry to reach up to the top of the sides of your dish. Take a little care so that you get a fairly flat, even layer of pastry that fills the dish.
When you’re happy with that layer, brush all the surface with a light coating of the egg white you set aside. I probably used about two-thirds of one white and stirred the rest into the filling mixture.
Once your oven has reached 400F /200C, bake the still-empty crust for 5 minutes, and then remove the dish from the oven. The egg white will have added a glossy white, sealing sheen to the pastry’s surface – that’s grand.
The pastry may have risen a little in places, so gently push it back down so that it’s lying flat on the base of the pie dish.
Keep the oven set at 400F /200C because you’re now ready to add the filling and bake your quiche.