I'm making black buttercream for a cake and added cocoa powder, brown Wilton color & black Wilton color and now it tastes funky Has a slight bitter after taste.

I tried fixing it by adding Princess emulsion, butter emulsion and orange emulsion but still doesn't taste good... Any tips on fixing it? I need to use it by tonight for a cake for tomorrow morning. TIA!

I have never been able to pull off Wilton black. It always tastes awful. I'm sorry! I would make a new batch and use Wilton Juniper and Americolor black. I never have a bitter taste with that route and I don't even start with chocolate buttercream.
Good luck!

And stick to pure vanilla.

All those other flavours just made it worse and worse.

I always, just use the americolor black. I never add anything else with it. If people don,t like chocolate, then you wouldn,t want to add that in. So, as it sits, it will turn darker, so be careful as to how black you get it.