This is a style that can only be done on really long hair.
Begin with Barbie bangs, as described in this post. Part a row parallel to the part already in the hair, and then pull the rest of the hair back temporarily. Beginning near one ear, dutch braid the row until you run out of hair above the ear. A cornrow is just a skinny dutch braid.
Braid all the way down and add an elastic.
Bring the end of the braid around the back and up to the side above the ear. Divide the tail end into two sections, loop each in half so the ends cross over, and use a mini clip to hold the bow shape down to the scalp.