The secret was in the rice flour (which gives you extra flavour and a fine texture), and, so she said, using the food proccessor, which by it's nature cuts through the shortbread - giving you a more crumbly texture than when you use a normal food mixer, although I still prefer to make it by hand.
It's been bookmarked for anyone else who wants to try it on the virtual recipe drawer that is Bookmarked Recipes - your one-stop shop for tried and tested recipes from the food blogger community updated every Monday, which I'm also hosting this week.
Since the original recipe was lost during a couple of moves, when I started making shortbread again - for our second ever assiette of desserts last July - I consulted my college text book - Practical Cookery by Ceserani, Kinton & Foskett. If you need the basics - basic techniques, basic recipes etc. you can always rely on finding them in there. My 8th edition is now so well used the spine and back cover have become detached. There's a heap of splatters and a bookmark however on page 715 - shortbread method II:
100g (4 oz) Plain flour
100g (4 oz) Rice flour
100g (4 oz) Butter or margarine
100g (4 oz) Caster sugar
1 egg, beaten
[I also added a handful of roasted chopped hazelnuts]
Sieve the flour and rice flour into a bowl. Rub in the butter until the texture of fine breadcrumbs. Mix in the sugar. Bind together to a stiff paste using the beaten egg. Roll out [on a floured surface] to 3mm (1/8 inch). Sprinkle with caster sugar, prick well with a fork [I didn't] and cut into shapes using a cutter. Place biscuits on a lightly greased baking sheet [I used a baking mat - guaranteed non-stick easy baking]. Bake at 180 - 200 oC/ Gas mk 4 - 6/ 350 - 400 oF, for 15 minutes or until golden brown. Remove with a palette knife on to a cooling rack.