I know I am mad, but...

[FrankWippery]

It's my sister's 30th birthday next weekend. Getting past the fact that she is disgustingly young, I have agreed to make a cake for her surprise party.

BIL says there will be 32 adults and 6 smalls, so guess I need to make a cake to serve 40 so there's leftovers for meeeeee

Now, I reckon 10" or maybe 12" square should do it. Is this about right or am I massively underestimating? My plan is to do a square cake, sponge, and cover it with fondant icing and will cheat with little decorations from a fab cake accessory shop up the road.

So...is this the right size, and if it is, what's the best recipe to do? Madeira or basic sponge? Will fill with a buttercream/jam. The downside is I have to get it from London to Sussex, but I'll cross that bridge next weekend somehow .

Any tips would be massively appreciated. I am very capable with baking, but have only ever done big cakes of the wedding/fruit variety.

Thank you anyone who can help.

Here is a good portions guide, and here is a good sponge recipe. I think I increased the quantities in proportion to 8 eggs for an 8 inch square cake, but that might have been overkill as I wanted quite a deep cake. Good luck with it!

Try a tray bake tin or make lots of fairy cakes!

Wem - that's a great guide, thank you for that. I think I'm going to do an 8" square and top it with a 4" square, thank you also for the recipe link - I suppose it wouldn't hurt to try it beforehand

PPN - I had toyed with the idea of a gazillion fairy cakes - I did these for my brother and sister-in-law's wedding, but I just haven't got the time this time to do that.

BIL has organised are rather special surprise party for DSis and I really want to make the cake as spectacular as I can muster. It may or may not involve large quantities of gin...