My grandmother's recipe.
Ingredients:
4 oz butter
1 tbs golden syrup (possibly you could use dark corn syrup or light molasses)
1 tbs cocoa powder
1 tbs sugar
8 oz digestive biscuits (graham crackers) or dry ginger biscuits
4 oz of golden raisins (sultanas)
8 oz Semi-sweet dark chocolate (I used 54%)
Method:
Melt butter, golden syrup, sugar and cocoa powder together over low heat.
Meanwhile, crush the biscuits in a ziplock bag with a rolling pin until smaller than pea size, but with some texture (not powder)
Add golden raisins and crushed biscuits.
Put the mixture into an 8 inch loose bottomed shallow metal pan and pack down evenly with the back of a spoon.
Refrigerate until cool.
Melt the chocolate, and pour over the top. Allow to set.