1.Preheat oven to 180oC. Grease and flour a 22cm - 23cm ring cake tin.
2. Stir the cocoa and boiling water together until smooth. Cool thoroughly.
3. Beat the butter, sugar and vanilla essence together until light and fluffy.
4. Beat in the eggs one at a time, beating well after each addition. Beat in half a cup of Craig's Blueberry Jam.
5. Sift in the self raising flour and pour in the cooled chocolate mixture. Fold together carefully.
6. Spread into the prepared cake tin.
7. Bake for 40 minutes or until a skewer inserted comes out clean and the cake has shrunk from the sides of the cake tin. Cool in the cake tin for 5 minutes before turning out on to a cake rack to cool.
8. When cool, split the cake in half or three layers horizontally and spread the cut layers with the remaining Craig's Blueberry Jam. Join together. Dust with icing sugar or spread with the thick chocolate glaze.
To make chocolate glaze:
Heat chocolate chips and cream in a microwave proof jug for 1 minute in a microwave on high power. Stir until the chocolate has all melted and the mixture is smooth. Smooth on to the cake while still warm.