Perfect Shortbread

I haven't made shortbread in years, but it is one of the few things I remember making more than once when I was small. The memory of eating pure sugar and butter mix sticks in my head more than the actual shortbread, however, and my fondness for it comes more from tartan wrapped packages of shortbread in hotel rooms rather than homemade. Nonetheless, I read this article on how to make the perfect shortbread, and I was curious. It is an excellent recipe, definitely a biscuit that stands up by itself, as opposed to being the foil to cream and fruit.

I did not have any trouble finding rice flour in the supermarket, but if your local doesn't stock it, I would suggest trying a health food shop, or an Asian supermarket.
My notes are in italics.

Ingredients
115g butter, at room temperature
55g caster sugar (I like to use golden for flavour)
Good pinch of salt
130g plain flour
40g ground rice
Demerara sugar, to finish

Method
1. Pre-heat the oven to 150C. Put the butter into a large mixing bowl, and beat with a wooden spoon until soft. Beat in the sugar and salt.
2. Sift over the flour and ground rice and mix to a smooth dough; if it doesn't come together, add a little more butter. I found I needed more butter here, and used my hands to finally bring in together.
3. Line a 15cm cake or tart tin with baking parchment, and pat, or lightly roll, the dough into a shape slightly smaller than the tin. Alternatively pat out to 1cm thickness and cut into biscuits and put on a lined baking tray. Put in the fridge to chill for 15 minutes until firm.
4. Bake for around an hour (about half that for biscuits) until cooked through, but not browned. Take out of the oven and cut into fingers, slices or squares. I made mine into biscuits, and at 150C in my (very weak) oven they took over an hour to cook.
5. Allow to cool for a couple of minutes, then sprinkle with demerara sugar and transfer to a wire rack.