I have a concrete slab wall that I am putting 2" rigid insulation against and then studding a wall over the insulation. Of course the concrete wall goes in and out and I have my floor plates in place already so there are some areas where the 2" fits nicely in to place behind the floor plates and I can stud with no problem. Other places the insulation sticks out which in turn makes the stud come out further. Has anyone ever cut grooves in rigid insulation and any suggestions how to do it easily? This will allow me to sink the studs further back in the insulation.

I know I should have come out further from the wall to compensate for this but I didn't so I am now stuck dealing with it. Luckily, I only did one wall so I know what to do on the rest of the walls.