Preheat oven to 180C. Sift flour, bicarb soda and spices together.

Cream butter and castor sugar in an electric mixer until light and fluffy.

Add egg and treacle and mix well. Add flour mixture and mix well to combine.

Roll into small balls and roll in raw sugar. Place on lined oven trays and flatten slightly. Allow room to spread.

Bake for 10 minutes, until crisp. Remove from oven and cool on trays for a few minutes before lifting onto wire racks to cool.

To make the butterscotch cream filling, melt sugar in large, heavy-based frypan, stirring with a wooden spoon.

Remove from heat, add cream and stir until combined. Set aside to cool.

Place butter in an electric mixer with a whisk attachment and whisk until light and fluffy.

Add caramel and continue to whisk until combined. Sandwich biscuits together with butterscotch cream.