2 oz/55g caster sugar
1 pinch salt
7 oz/200g plain flour or all-purpose flour
Yield for fingers (much preferred) is around a 18cm (7 to 8 inch) square. For Petticoat Tails it will yield a chunky 20cm (8 inch) circle.
Mix the butter (if using unsalted butter then ADD a pinch of salt to it) and sugar together (preferably with a wooden spoon) until it is pale and creamy. Sieve the flour into the bowl and mix well. Put a small amount of flour on your working surface and place the dough on this. Knead well (on a very lightly floured surface). The longer you knead, the better the shortbread will be.
Roll the mixture out to shape and size of the tray. For fingers, roll out to about 2.5 cm (0.8 inch) thick. For petticoat tails it needs to be a little under 1/2 inch thick to yield a chunky circle of about 7 to 8 inches.
For fingers: put it into baking tray, slice into fingers, prick all over with a fork.
For petticoat tails: using fork prongs, from the outer edge towards the centre, indent the top about a 1/2 inch all the way round to give it a nice crinkly edge – sort of like the teeth on a cogwheel, then prick all the way round the middle ideally rotating the fork or the pastry to give a pretty effect when cut. Carefully lift and support the decorated circle and place and fit snugly into the circular baking tray. Score lightly (to about halfway downwards to bottom of the tray) into eight equal segments.
Bake 40-45 mins until lightly golden, 165C degrees (325F / Gas Mark 3 ).
For petticoat tails it’s customary to sprinkle liberally with castor sugar.