Put the dry ingredients in a bowl and mix by hand.
Cut the butter into small cubes and put it in the bowl.
Then rub the butter with all the ingredients until you have a crumbly dough.
Add part of the beaten egg and knead to a dough ball. The ball must feel smooth. If it's too dry, add some egg when it's too wet, you'll add some flour.
Make a ball, wrap in foil and put away to cool. At least an hour.