So I just got the confetti cakes book and I love it (the chocolate cake is soooo good
But I had a problem with the SMBC recipe. I followed it to a T but by the time I was done making it it was super runny. The mixture was not warm or any thing so I dont think the butter melted but to be safe I put it in the refrigerator over night to try to firm it up. When I pulled it out it was still pretty soft but it got grainy
Any advice on what happened?

Exactly how did you make your icing? It would help if you stated your ingredients and method. Then maybe I could help you figure out what went wrong. I make SMBC regularly and have never had any problems with it.

Did you whip it enough? I made IMBC tonight and thought mine was going to be too runny, then all of a sudden it came together, thick and whipped.

Could you describe what you did? I had some soft SMBC issues as well and I think I know what happened.

I had the same thing happen to my chocolate smbc over the weekend, it was very runny. I thought it was because I added the chocolate with the vanilla instead of adding it at the end. I had left the butter out overnight to soften, maybe it was too soft and adding it to the warm egg/sugar mix melted it? I put it in the fridge and it still stayed like whipped cream. Tasted great, but didn't hold up so well! I had made the regular smbc the weekend before and it was perfect, not sure what made the difference..

Sorry it took so long to reply, here is the recipe that I used
2 3/4 cups (20oz) plus 3 tbsp sugar
1 1/4 cups (10oz) egg whites
2 1/2 cups unsalted butter
vanilla extract 1/4 cup plus 2tbsp

whisk together sugar and egg whites in stand mixer bowl, set over pot of boiling water whisking constantly untill sugar has dissolved and mixture is hot.
whip in stand mixer untill stiff peaks form and meringue is at room temp.
Using paddle attachment on low speed beat in butter a few cubes at a time.

Dose any one know what happened to my buttercream?

1/4 cup of vanilla is WAY too much. So that may be it. Also, I don't think there is enough butter in that recipe. I'm not sure what the white/sugar ratio is on my recipes, but I normally have 6 cups of butter in there.

That could be part of the issue - I use the same recipe from Confetti and never put all the vanilla in, it really doesn't need that much.. Maybe the eggs weren't whipped up stiff enough? I'm making it again this morning, I'll be scrutinizing every step!

So finally I was able to try this recipe again and I made sure to whip the eggs FOR EVER lol they were very stiff I also made sure the butter was not too soft. After all 2 1/2 cups of butter were added the buttercream was still runny so I started adding more butter, but I was all out of unsalted butter well I started adding some salted butter. I ended up adding a whole 2 more cups. So after 4 1/2 cups the buttercream was perfect!!!! Thinck and smooth, I decided to not add any vanilla and added about a cup of carmel and some carmel candy flavoring I had OMG it was soooooo good, the salt in the butter kinda gave the buttercream a salted carmel flavor to die for
So thank you all for your suggestions!!
By the way I will be pairing this with chocolate cake, fleur de sel....