In a large bowl, mix together the oatmeal, plain flour, ground ginger, bicarbonate of soda and the cream of tartar and put aside. Also, grease and line a 23cm square cake tin with oven paper. Melt the butter or margarine in a saucepan over a low heat, and then add in the oat mixture. Mix well with a large spoon before adding in the brown sugar, golden syrup and chopped walnuts. Stir the mixture till all the ingredients are well incorporated, and pour into the prepared cake tin. Press the mixture into all of the corners and flatten out. Bake in the oven at 180`c, for 30-40 minutes. Remove the cake tin out of the oven and allow the gingerbread to cool down completely in the tin. Melt the dark chocolate and pour over the cooled gingerbread. Spread out with a palette knife and allow to set. When the chocolate has hardened, turn the gingerbread out on a chopping board and cut into squares using a sharp knife. Suggested accompanying wine: DELICATA Casella Moscato Sweet White Wine