Cream the butter and caster sugar until pale and fluffy
Sift in flours and mix until just combined but still crumbly
Press into a ball and divide the dough equally
For petticoat tails: Press into a round loose bottomed metal tin, decorate and mark into 8 wedges
For demerara rounds: Roll into a log, wrap in clingfilm and refrigerate for 20-30 mins
Unwrap the log and roll in demerara sugar then cut into 8 discs and place on a baking sheet
Bake both in a preheated oven at 160°C - remove the rounds after 20 minutes, leave the petticoat tails in for a further 15-20 minutes until light golden-brown
Leave to cool in the tins for 5 minutes
Move the rounds straight to a cooling rack
Cut the petticoat tails into wedges along the marked lines and dust with caster sugar, then move to a rack to finish cooling
