[Cob] electrical boxes

[Tys Sniffen]

Hey folks,

While I know I'm going to be chiseling out some spots for switch boxes and
outlets (decided not to decide where they went before cobbing up the walls)
I still am wondering: 
How have you handled the switch/outlet box connection to the wall? Just cob
or plaster it into a hole big enough for it, then screw on the outlet and
plate? Add dead men so you could screw it in? 
Just looking for some advice on this next step
Tys