Chocolate fudge sponge with vanilla buttercream.
Bit annoyed with myself as used a very tasty, but slightly unstable sponge and forgot (it was 1am and had been a long day) to use some dark choc ganache as a crumb coating around the outside to stabilise the cake before I put fondant on it. As you can see the cake settled a bit overnight as a result. Doh!
Nevermind, I'll remember next time!