Sift the flours together into a mixing bowl, add the sugar and mix well. Add the butter. Using just the tips of your fingers, rub the ingredients together until the mixture resembles fine breadcrumbs. When all the butter is evenly mixed in, make a well in the centre and add the syrup, vanilla and the egg. Mix well, drawing in any of the flour left at the side of the bowl, and stop as soon as a ball has formed. Place the ball of dough on a sheet of parchment. To make your dough as even as possible you can use rolling guides; which you can buy from specialist shops. Or improvise by using a couple of wooden spoons, just like the image below.