Jam donut shortbread

Method
(Makes 12-14 sandwich cookies.)
In a large mixing bowl, cream the butter and sugars until light and fluffy (about 3 minutes).
Combine the flours and salt, and add to the butter. Mix gently until the dough just comes together – do not overwork it.
Roll into a ball and then gently press the dough into a disc shape, 2-3cm deep.
Cover in clingfilm and place in the fridge for at least two hours for the dough to rest.
Once ready for baking, set the oven to 170C. Remove the dough from the fridge and allow to soften slightly (this will make it much easier to roll out).
Roll out the dough to about 5mm thick and use a cookie cutter to cut into desired shape. Place cookies on a lined baking tray and bake for 20 minutes.
While the shortbread is baking, combine the remaining caster sugar and cinnamon.
As soon as the biscuits come out the oven, spoon over the sugar mixture to coat the top of the biscuits completely. The heat from the biscuits will help the sugar to stick, so be sure to do this while they are hot.
Leave the biscuits to cool. Once you are able to handle them, gently scoop out each biscuit and shake off any excess sugar.
When completely cool, smear one teaspoon of jam on half the biscuits, on the non-sugared side.
Press together with the other biscuit half to create jam-filled sandwiches.
To serve
You can use your favourite store-bought jam for the filling, or make your own (see seasonal jam recipe).