I think this is only the third birthday cake I've made for the Swan Whisperer in all the years we've been married! And the other two were fruitcakes.
For the cake:
The same weight (c. 240 g) of butter/baking fat and sugar.
2 tbs cocoa powder, made up to 240 g with self-raising flour and a pinch of salt
2 tbs very strong black coffee
Cream fat and sugar together; add the eggs one at a time and beat in, add the coffee, and finally fold in the flour/cocoa powder mixture. Divide into 2 21-cm sponge tins and bake in a moderate oven (Mark 4) for 25-30 minutes, until a skewer inserted comes out clean.
For the cranberry filling:
About 75 g fresh cranberries (you don't need a huge amount)
Juice of 2 oranges (1 if it has made plenty - you want about 4-6 tbs)
2-3 tbs sugar (make it slightly sweeter than if you were making cranberry sauce for the Christmas table)
Put all of the above in a saucepan, put a lid on and cook until all the cranberries have gone "phut" (which is the noise they make as they cook). Allow to cool.
For the ganache topping:
1 bar Green and Black's Organic dark chocolate
1 large tbs crème fraiche
Any surplus juice from the cranberries
Melt the chocolate in a bowl over hot water (or in a double saucepan, if you have such a thing); stir in cream and juice.
Have the nicer cake, if there is one, on the top. Spread the other one with the cranberries, then put the second cake on the top, and spread it with the ganache. Allow to cool thoroughly and keep refrigerated. Decorate as liked.....