after reading many a fiesty debate over the proper flours and shapes for shortbread I've settled on this recipe. I have also made a traditional rice flour version based on these proportions but found it too granular for my liking, although a finer rice flour would probably work well.
100g fine to medium wheatflour
100g butter (salted or unsalted and cultured, depending on your liking - I like salted)
50g caster sugar
50g pure cornflour
cut butter into flours (this can be done with a food processor) and then finish to a coarse crumble mixture by hand.
add sugar and mix.
dump the dough on a clean work surface and bring it together first by squeezing, then gently kneading.
the more kneading, the firmer the resulting biscuit, a fact that can be used to suit different purposes. A light crumbly dough that's been barely kneaded can be difficult to cut when cooked so it's best to shape this kind before baking. Otherwise the dough can be spread on a tray to the desired thickness and baked in one piece, then cut while still warm. traditional shapes include fans and bars pricked with a fork.
baking
baking shortbread requires the perfect balance between time and temperature. in most ovens 160°c will work best. the dough needs a high enough temperature to maintain shape without melting before it's cooked, but not so high that the butter in the dough begins to brown. baking time will depend on thickness, but as they'll crisp up when cooled it's best to err on the side of less time if unsure. as a guide, 8mm thick bars would require about 20 minutes. when the base is no longer doughy they're probably about right.
the delicate texture of the crumb is easily ruined by condensation so they need to be transferred to a cooling rack as soon as they come out of the oven.
hazelnuts
obviously there are numerous flavoursome things you can add to shortbread if you're not a traditionalist. my favourite is a handful of roughly chopped roasted hazelnuts.