By Cocotte of Barcelona. This gorgeous frock, and many more, can be found at the website, the blog, and the Etsy store.
The irony is, I already HAVE a little black dress that's pretty much identical to this one. Same tulip skirt, same pockets at the side, same buttons, except the buttons on mine are down the back, not the front.
However, as I'm sure my female readers will understand, Frocklust knows no logic.