How do you make those buttercream clouds. It just looks like a cloud on the cupcake. What tip do you use?

Do you have a picture?

http://www.justaddcandles.net/Cupcakes.html#2 Like the white under the fondant disks. This is exactly what I'm doing.

Round tip, 12 or 1A or just a coupler with the notch opening turned down. Spiral from the outside in, to pipe the 'swirl'.