Week old buttercream - ok to use?

[pigsinmud]

I made too much buttercream last Friday for a batch of fairy cakes. Making another batch now - is this buttercream ok to use or do I need a fresh lot? It has been in a lock & lock container in the fridge....looks ok!

It'll be fine. Just give it a sniff to be sure.

Butter keeps for weeks and sugar is a preservative.

Yes, you're right. Never though that butter sits in the fridge for weeks! My mother looked a bit disgusted yesterday when I said i was going to use it.

I've used buttercream quite a few weeks after making it before, it seemed fine to me.

If it is just icing sugar and butter, it will last as long as the best by date of the butter, if you add milk as long as the best by date of the milk.