Absolutely agree with lilolil if for a child's birthday. The first Barbie cake I did for dd1 from the Nigella recipe in Domestic Goddess came out like a stone. I just iced the darn thing anyway. It looked fab so who cares. If the new one is good, keep it and eat it after they've all gone home!
If you're going for the trifle option, the deconstructed one with lemon and raspberries in Domestic Goddess is yummy.