Preheat oven to 400 degrees F. Line a baking sheet with aluminum foil. Lay bacon strips on baking sheet and cook for 20 minutes or until crispy. Transfer to a paper towel-lined plate to drain.
When bacon is almost done baking, toast bread until golden.
Lay one piece of bread on a plate, spread with 1/2 tablespoon mayo. Top with cheese, ham, and turkey.
Spread one slide of another piece of toast with 1/2 tablespoon mayo and place mayo side down on the ham. Spread other side of the same toast with 1/2 tablespoon mayo.
Top with lettuce, tomato, bacon, and avocado. Spread one side of the last piece of toast with remaining mayo and place mayo side down on the sandwich.
Insert a frilled toothpick into each quarter of the sandwich. Use a sharp knife to cut the sandwich into equal quarters. (The toothpicks will keep things from falling apart.) Plate the sandwich quarters either standing up or on their sides. Serve immediately with fries, chips, or your favorite side.
Notes
Feel free to cook the bacon on the stovetop or in your air fryer. Use any kind of cheese you like, or omit altogether.