My friend Erin has written so many guest blog posts  that use this frosting recipe that I decided it was time it had its own blog post.
(Before, it was buried in a post about cake pops .) No more - here's the recipe. It's by Buffy Vance of Madeline's Confectionary in Urbana .
Buffy's Crusting Buttercream Frosting
1 cup butter, softened
1 cup vegetable shortening
2 pounds powdered sugar
1/3 cup water
1 tablespoon vanilla
Cream butter and shortening together and add most of the water. Add the sugar and beat on low until mixed. Scrape the bowl and beat on low an additional five minutes. Add vanilla. For thicker frosting, use less water.