Okay i already made my buttercream can i add coco to it now to make it chocolate????
Yes! I do it all the time
Mmm.....oh wait, I got distracted by the word chocolate. LOL
Yes! Add cocoa powder or melted, cooled unsweetened baking chocolate. You'll need to add some more milk or water too. Just add it a tablespoon at a time till you get to the consistency you're looking for. I also add a tablespoon or two of light corn syrup when I make chocolate buttercream, for smoothness.