Now make the ganache. Brake the chocolate into the even smallish pieces and start melting it. I just use 20 s short blasts in the microwave on the full power, stirring thouroughly after each. You do not need to melt it completely just to start it.Bring the milk to the boil, I do it in the microwave as well, it will take just 2-3 20 s blasts on the full power. Stir together until silky smooth and uniform. Pour the ganache over the top of the cake, making sure that it covers the peanuts, do not worry if it runs on the sides of the cakes, it will make it look even better. Leave the ganache to cool and to set and the cake is ready to be served!