I’m with Ellie on this one. I use equal parts by weight of butter and cream cheese and about twice as much powdered sugar by weight as the butter/cream cheese combined. Sometimes I add more sugar if I need it extra stiff and if I get it so stiff that my kitchen aide can’t even mix it, then I thin it down slightly with 1 tsp of heavy whipping cream at a time (a little tsp can make a big difference). Good luck!
Maria @ http://www.facebook.com/rooneygirlbakeshop or http://www.rooneygirlbakeshop.com
