Perfect, even if you don't have a food processor you can still do this with room temp butter if you're going to use it right away. Made 18 cupcakes.
Thanks for posting this. I had a recipe that I wanted to make for squares that needed a cake mix and I didn't have one. This worked perfectly. I didn't have self rising flour (actually I've never seen self rising flour in our stores) so I used Self-Rising Flour.