I need a recipe for SUPER smooth BC. The recipe I usually use is good under fondant, but it doesn't smooth out very nicely as the main icing on a cake. I've tried it all... Viva paper towel, a hot scraper, a high density foam paint roller, nothing gave me a perfectly smooth surface. If you have a recipe/method that works well for you, PLEASE let me know! Thanks!!
I like Serious_cakes buttercream recipe.
It's really nice and smooth, it took me some practice to make it like she does on her youtube videos, but I've found that if I really cream the butter and shortening good, it works the best! HTH
For a really smooth icing, try a Swiss Meringue Buttercream (SMBC) or Italian Meringue Buttercream (IMBC).
They don't crust, but are so incredibly smooth that once you've used them any recipe that uses icing sugar will seem grainy...
Sugarshack's recipe is awesome. Be sure to follow all of her directions, that 6 minutes at the end is important.