I'm doing a quilled cake this weekend for a girl's 7th birthday and am wondering if I can use buttercream? I know it's traditionally done on fondant but I'm pretty sure 7 year olds would rather have buttercream. Will the pieces stick? I was thinking about putting each petal individually on the cake rather than as one whole piece so it wouldn't be as heavy. I don't know, I've never done a quilled cake before. Any advice or experience doing this type of cake would be appreciated!

You mean, making the quills out of buttercream, or sticking fondant quills in buttercream. I would imagine fondant quills "glued" with a little bit of buttercream on a smooth iced buttercream surface should be fine. Are you quilling the sides as well? I think using smaller pieces would be a good idea, and perhaps using small pins or toothpicks to support while the "glue" dries would help.
 

ASorry I should have clarified - I'm making the quills ahead of time out of gumpaste. It's a two tier cake and I'm planning to have the quills (flowers) on the side of the bottom tier and sticking out on the top tier (like up in the air, 3-D...does that make sense?) thank you for the help!