Quick, Easy, child friendly cake?

Ok, it's DD's birthday this Sat and I want to send a cake to child care on Friday... but the catch is, it needs to be super easy and quick to make and suitable for child care. Any suggestions? I'll be making it Thursday night after work and can't be up all night... Any ideas?

Here's what I did for DS's birthday cake:

Goat's butter melted in microwave
Add butter, 3 eggs, 6 spoons sugar (should be honey but DH ate it all), 8 spoons self-raising flour, 3 bananas in smallish pieces to a blender.

Blend.
Into loaf tin.
In oven for 25 minutes.

Make pink icing and plonk on top once cake is baked.

TBH, any cake is quick to make in a blender! Nigella Lawson swears by it and that's how she bakes a cake most days, apparently. BTW, I checked with Nursery for allergies first. Only DS is allergic so I only had to cater for him! Other mums either don't do anything special for DS (not a problem!) or buy some dairy and nut free jam tarts or something like that for him (and God bless the mummy who did that!).