Hmmm, strange. Mine never did, so I started adding all kinds of stuff to it...
I added a scoop of tofutti cream cheese, then I added something else, can't remember what it was - maybe some sugar? I just know I had to add something to it to get it to set up.
It wasn't something I'd try again, so I didn't write it down. My favorite frosting now is a ganache from David Lebovitz, using butter, bittersweet chocolate and water. (Can you use butter? I can...)
For the ganache frosting:
10 ounces bittersweet or semisweet chocolate, coarsely chopped
½ cup water
¾ cup (1½ sticks) unsalted butter
To make the frosting, melt the chopped chocolate with the water in a heatproof bowl set over a pan of barely simmering water, stirring occasionally until melted. Remove the bowl from the pan of water.
Cut the butter into small pieces and whisk them into the chocolate until completely melted and the ganache is smooth. Cool until spreadable, which may take about 1 hour at room temperature.
This texture of this frosting is kinda like the blender one, where it's not sugary at all, and kinda pudding-like in consistency. But it's not as sweet, and it's a little softer. But still nice and easy to spread, and beautifully glossy.
I used a salted butter, because that's what I always have. I'm sure it will be better with unsalted, but I kinda liked the slightly salty taste to it.