Try to get a good size whole round bread to start off with...some are too small for this sandwich and you won't be able to get much of the ingredients in the bread...or pick up two small loaves if that is what is available
Slice off the top third of the bread loaf keeping it whole, set aside.
Hollow out the bottom of the bread getting fairly close to the edges, but be sure you don't poke through the bread wall. Reserve and freeze the bread crumbs for another use...perhaps to add to your Thanksgiving Stuffing recipe!
Combine mayo, Italian seasoning and cracked pepper. Brush the inside of the hollowed out bread with half the mayo mix. Set shell and extra mayo aside.
Saute onion, red pepper and celery in olive oil till crisp tender...don't let it cook too long...you want the veggies to be somewhat crisp, but cooked.
Arrange half the ham slices in the bottom of the bread, layer on half the veggie mix, and half the cheese. Spread the remaining mayo mix over the cheese. Repeat layers using more ham, the remainder of the veggie mix and the cheese.
Replace the bread top. Wrap loaf tightly in heavy duty aluminum foil. Bake at 400 degrees for 30 minutes or until heated through thoroughly
Remove foil and let sit on cutting boad for 5 minutes...cut into wedges and serve....SO GOOD!!!!