On a griddle or in a large skillet*, cook bacon until done and set aside.
Spread mayonnaise over the bread and assemble sandwiches with bacon, chicken, avocado slices, optional tomato and pepperjack cheese.
If you are going to cook the sandwiches in the bacon drippings, scrape or pour off all but about a tablespoon of grease, heat over medium heat and place sandwiches into the pan.
If you don't want to use the bacon drippings, wipe out grease and spread a very light coating of mayonnaise on both sides of the sandwiches before placing into the hot pan.
Cook, flipping once, until both sides are browned and cheese is melted.
Serve and enjoy.
*I like to use the white meat of a rotisserie chicken for this, but you can use any type of cooked chicken you like. Sliced deli meat is also a good option!*If using a skillet to make the sandwiches, you will probably have to cook them in two batches. Heat your oven to 150°F and place the first batch of cooked sandwiches inside to keep warm while you finish the second batch.