There is no outlet on this side of the wall where the wife wants one. And what the wife wants....well you might know the rest!
But there is an outlet directly on the opposite side of the wall! I took the outlet out and sure enough, mounted to a stud. Measured, went around to the other side, measured, and started cutting without really thinking this through. The wall is about five inches thick. I realized I couldn't put the boxes "butt to butt" as they would never fit. So I thought (badly) thaT I could stack them...not a good idea with 12/2 cable unless your top box has no bottom! So that's kind of were I am at...either find or make a box with no bottom, or find some other way to mount this outlet. Do they still make Edison Clamps and would that be acceptable?
The existing box should be on one side of the bay against one stud. Put the other box on the other side of the same bay. You'll connect them with a length of 12/2 which you'll install before you install the new box in the wall.