Why has my buttercream curdled?!

[skillsandtea]

I've made chocolate buttercream plenty of times before and it 's been fine but today it's gone all yucky and curdled. What's happened and can it be fixed or do I have to start over again. I need it asap as I'm baking my nephew's birthday cake! I've used 250g soft butter, about 400g icing sugar and about 70g cocoa powder which I mixed up with warm water before adding it to the mixture. But that was when it seemed to split. Could it be the warm water? Help please....

I would guess that it is the water. Oil (butter) and water don't really mix. Why did you put it in?

I think it's the water in the cocoa.

You might be able to fix it by adding more cocoa/icing sugar but otherwise you may need to start again.

If you do - sieve the cocoa powder and icing sugar together. Chop the butter into small pieces - the smaller the better. If you can gently warm the bowl (or put into a warm bowl) it'll mix more easily. If the icing is too thick when you've done all this then add a little milk.

Definitely the water. Next time, sift the cocoa powder in with the icing sugar.

Has it curdled or just split? If it's the latter I think you can stick it in the fridge for a bit to cool it then mix it back together not completely sure though!

It's more split I guess. I mixed the cocoa with water to make a paste so that it would look more like chocolate rather than a malt brown colour which is always much lighter than the chocolate sponge. It's worked fine before but maybe it's because the water was warm and I should have used cool tap water. The buttercream is going to be filling and a crumb coat so it's not part of the main decoration and won't be visible outside the cake. Should I start again? I make loads of cakes for home consumption and they always work but when I want to do something special for someone else they go tits up

What does it taste like?

It's disgusting. I'm binning it.