Hi, I am making 100 vanilla cupcakes I have been using the same recipe I usually follow but for some reason they keep sinking and shriveling up and not cooking properly in the centre.

Any ideas what could be wrong?
I have tried under filling, filling, over filling, turning oven up, down, etc
the mixture looks like it might be splitting slightly

what recipe do you follow for baking a large quantity?
I only have whats left in my cupboard to make them which is eggs, margarine, caster sugar and Self Raising flour and vanilla extract.
what quantities do you use?

I need to make them now for collection either later this evening or tomorrow morning.

HELP!!!
Thanks xx

other people will likely have other thoughts, but do you need to mix the batter for all 100 at the same time? do you have an oven with that capacity? if not, make smaller batches (2-3 dozen at a time) and keeping mixing up and baking them as you go. good luck. won't take too long.