easy iced birthday cake recipe please?

[MamaChris]

I'm not a cake maker, but have promised ds1 (3) an octonauts cake for his birthday. I've bought coloured icing, and think I need to make 2 cakes so I can cut out ears from the second. For this reason I don't want to make a sandwich type cake, as this would mean 4 cake tins, which I don't own and wouldn't fit in the oven. Can anyone suggest an easy one layer cake suitable for icing that I can make whilst looking after 3mo twins?

cococakecupcakes.blogspot.com/2009/09/octonauts-themed-birthday-for-dakota.html
I had to google Octonauts because my dcs are older they had to have Roley from Bob the builder and swiss roll Thomas the tank cakes.

If I was going to do the cake above I would just do a victoria sandwich with butter cream for the filling.
If you want to do the ears sticking out then you can just use solid icing for the ears and a round cake for the head.

Either cut your cakes in half with a serated palette knive to get your four, or I often use a brownie recipe so I don't have to worry about cutting and filling if I've got complicated shapes to cut and icing to cover. I'd cover the ears separately and then stick those to the cake rather than trying to cover it as one iyswim.