Slice bread 11 - 13 times (you will need a very sharp knife for this!) Do not slice completely through the bread, instead leave a small amount unsliced at the bottom of the loaf to keep the sandwiches together.
Ball up a few pieces of aluminum foil and place in the bottom of the crockpot to keep your bread up off the top of the slow cooker. Add 1/4 cup water to the bottom of the slow cooker.
On countertop, layer cheese and slices of ham or turkey, then add banana peppers and onion slices. Sprinkle with Italian Seasoning and salt and pepper.
Place each layer in between two slices of bread. (Be sure to drain the banana peppers so that they don't make the bread soggy.)
Wrap tightly in aluminum foil and cook for 2-4 hours on low. (We baked ours for about 4 hours and they were perfect!)
Remove from foil and slice into sandwiches.
Drizzle olive oil or add a little mayo to the inside of each sandwich if you'd like, and enjoy!