Preheat the oven to 190*C/365*F/ gas mark 5.  Butter an 8 inch square baking tin and line with paper.  Set aside.

Cream together the butter and sugar in a bowl, until well combined. Sift the flour into the bowl, along with the ginger, cinnamon, allspice, cardamom and salt.  Mix together with a wooden spoon until the mixture is well blended and crumbly. Remove 54g (1/3 cup) and set aside.  Whisk together the buttermilk, molasses and beaten egg.  Stir the bicarbonate of soda into the main bowl of crumbs. Add the wet mixture to this and blend well.  Pour into the prepared tin and then sprinkle the reserves 54g (1/3 cup) of crumbs evenly over top.

Bake in the preheated oven for 20 to 30 minutes or until a toothpick inserted in the centre comes out clean and the top springs back when lightly touched.

In a small saucepan, combine all of the sauce ingredietns.  Bring to a boil over medium heat, stirring constantly. Reduce to a simmer, and simmer over low heat, stirring occasionally for 4 minutes.

Serve the cake cut into squares with some of the warm sauce spooned over top.  Store any remaining sauce in the refrigerator.