Pattern: Butterick B4790.
If you use this pattern, I high recommend you make a mock-up first. The back part that is supposed to meet in the front at the waist came nowhere near where it should (when the rest of it fit just fine.) I had to alter the pattern to make it fit.
Oh, and this was the sewing project that spurred me to make my dress form.
I lined the front piece with muslin. Then, when it was sewn together, I realized the back piece was hella-heavy and constantly pulling the front up by their connection at the shoulders. To combat this I put 6 washers (yay a reason to go to Lowes!) along the front lower hemline.
Next I used at least 4 packs of black, double-sided bias tape to edge the entire dress and I set grommets at the front and back tie off points for the dress.