Essentially as Cook's Illustrated would tell it, done my way.
You'll need two 9" cake pans that stack together. Preheat the oven to 425ºF. We'll reduce it as we put the shortbread in...
- Throw 1 ¾ cups of all purpose flour, and ¼ cup of rice flour in a mixing bowl (or ¼ cup cornstarch)
- Dice 2 sticks of cold unsalted butter (16 tbsp's all up) into ½" cubes and toss in the flour
- Add 5oz of ultrafine baker's sugar (caster sugar) reserving about 1 tbsp (maybe a bit less) for dusting
- Throw in 2 good pinches of salt and mix on low for 3 to 4 minutes. You can also mix by hand.
- you should have something resembling large "crumbs"
- Line the bottom of a 9" cake pan with parchment, tip the crumbs in, and spread evenly with your fingers :)
- Press down with a second 9" cake pan, heavily, until you have a nice even cake
- Lay parchment down on a baking sheet and tip the flat cake out onto it.
- Even up the edges gently, pressing with a spoon.
- Cut a 2" circle out of the middle, and set aside (free cookie!). If you have metal cookie cutter leave that in.
- If you don't, it's easy to clean out the mess in the middle after baking, so don't fret
- Boost it into the oven reducing it immediately to 300ºF. A hot start is what we want, but not for long.
- Bake for 20 minutes, then remove and score into 16 even slices with a knife, then pierce each with a fork
- Back in the oven for about 40 more minutes (perhaps a few less) - until golden brown
When you pull the baking sheet out, move the parchment with shortbreads off onto a wire rack to cool for 3 hours. If you didn't have a cookie cutter in the middle, run your paring knife around the original hole again and toss out the spillage in the middle. Dust evenly with the reserved sugar and after cooling, enjoy with a cup of white English Breakfast or Irish Breakfast tea.