Put the flour, sugar and salt in a mixing bowl and stir. Cut your stick of butter into pats right on top of the flour mixture then take off your rings because it's about to get a little messy. Stick your hands right in there and start squeezing those pieces of butter into the flour until it starts to resemble pea-sized, coarse crumbs. Then break your egg into the mixture, still using your hands to mix it all together. It will come together into a nice ball of dough. If it's too dry add a tsp of water and continue to mix. If it's too wet add a little flour until you get it to the right consistency. It should stop sticking to your fingers when it's right. Super scientific. Wrap it up in cling wrap and let it chill out in the fridge for 30-40 minutes.