Need a kids birthday cake recipe please (for about 20 people) - no dairy, prefer oil if poss

[Wintersun]

Can anyone help?

Can it be Brownies? My recipe takes oil, eggs, sugar and flour... But won't make a proper cake, they go sort of squishy.

Fatless sponge mum used to make,don't have recipe here but so light, love it. Unfortunately used to ahve with lashings of shipped cream in it!

I'd prefer more of a 'classic' childs birthday cake. Could I just replace butter with oil? Anything else other than water and icing sugar to ice/top it with?