John Gilmer wrote:
For Idea 1, maybe another option would be to: remove the existing
sheetrock; sister 2x3 studs next to the existing 2x4 studs; cut the
existing 2x4's down to the level of the 2x3's with a circular saw
and/or Sawzall; the re-sheetrock with 1/2-inch sheetrock. Or, if
you have access to both sides if the existing wall, maybe tear it
down and rebuild it with 2x3's and sheetrock both sides with
1/2-inch sheetrock.

A variation is to remove the old drywall and add your "sisters" so
that they are 1/2" below the studs. Cut the new drywall to fit
between the old studs. ...,

That's an interesting idea. It would be easier than my idea, and it would
leave him with an enclosed wall next to the oven. Also, with the idea that
I had suggested, I forgot to include that the OP would have to cut back the
top plate and bottom plate, which may not be to easy to do.