Preheat a charcoal grill to medium.
Put a chicken breast between 2 sheets of plastic wrap.
Starting in the center and working outwards, pound it with the flat side of a meat mallet until 1/4 inch thick.
Repeat with the other chicken breast.
Spray the chicken with cooking oil and sprinkle the Italian seasoning over it.
Cook on the grill for 2 or 3 minutes per side or until cooked through.
You can cook the bacon on the grill too, or else cook it in a skillet or under the broiler, as you prefer.
Spread the mayonnaise over all the toasted bread slices.
Layer the lettuce, tomato, chicken, bacon, and avocado on 2 of the bread slices.
Top with the other 2 toasted bread slices and cut each sandwich in half diagonally to serve.
Put a decorative toothpick through each sandwich to help hold it together if you need to.
