I always use salted butter, I like the subtle tang it gives. The buttercream does not actually taste salty. Usually I use Waitrose or Lidl butter, but today I used Tesco butter. It didn't occur to me to taste the butter first.
I've just tasted this buttercream and it is very salty! I tried adding more sugar, and it's now sickly sweet salty buttercream.
Short of starting again (which means going to the shops) is there anything I can do? The party is tomorrow!