To make in a food processor which is the easiest and quickest way; put the flour and salt into the bowl fitted with a metal blade and pulse a few times to mix. Add the butter and egg pulse briefly just until the mixture comes together in a ball.

To make the dough by hand, put the flour, salt, and butter into a large bowl and with your fingertips mix until the butter is broken up into large flakes and coated with the flour. Add the egg and mix until the dough gathers into a smooth ball.

Place the dough into a plastic bag and let rest and chill for at least two hours or better still overnight.

Take out of the fridge about 30 minutes before rolling out.