Draping a robe a la francaise, or sacque. An eight part series! Click the tag or go to the tutorial page for links to all parts.
The pleats at back need to be covered. It's a little fiddly, but not really too hard!
Cut a rectangle of fabric slightly longer than your back and slightly more than double the length from the top to the bottom edge of the shoulder straps.
Fold the bottom edge under and pin to the back.
Fold the edge of the rectangle so it lines up with the shoulder strap.
Mark the top edge with a pin, then very carefully cut a slit from the edge of the rectangle to the edge of the strap.
Fold the excess under on the back half of the binding.
Repeat on the other side.
Then fold this around to the other side. Sew into place. Use a spaced backstitch on the right side, and just whip it down on the wrong side.