Recipe from yammiesnoshery.com
New, easy and awesome way to make chocolate buttercream with only TWO ingredients: butter and chocolate. That's right. Get those arteries nice and clogged. It's actually sort of like a whipped ganache only with butter instead of cream. All you have to do is melt some butter and chocolate...
Then chill it well and whip it.
1 lb. butter (2 cups)
12 oz. chocolate chips or chopped chocolate (2 cups)
Melt together in double broiler or in microwave with power turned down a little (in case you haven't noticed, I always like to turn down the microwave heat when I'm melting chocolate). Whisk together until combined. Throw it in the freezer while the cupcakes bake until it's pretty firm. Beat for at least 5 minutes until fluffy. Frost cooled cupcakes immediately and then chill. I suggest serving them cold. That's how they're the best.