How do you make the ruffles like on the bottom of this cake? The photo is kind of bright, but I think it's fondant ruffles surrounding a few pink gum paste roses...

Also, can fondant ruffles/roses be added to a buttercream cake or fondant cake only?

http://www.thecakeblog.com/wp-content/uploads/2011/05/pearl_ruffle_cake3.jpg

I believe they're made like this:

http://jessicakesblog.blogspot.com.au/2011/01/feature-and-tutorial.html

Maybe rolled a little thinner, and folded a bit less evenly. I can't help with your buttercream question, sorry.