Stripped bolt in FD clamp

Somehow managed to shear the clamp bolt on a NOS Deore XT derailleur. At first I thought this was toast but it appears it was threaded into a nut on the other side. I first drilled a hole into the middle of the alloy bolt and then tried tapping out with a screwdriver and hammer, with no success. It appears the nut has two pieces of metal holding it in place on the other side.

Any tips or advice for removing this?

Thanks