Heat a skillet over medium heat. Brush both sides of pita bread with olive oil and sprinkle with garlic salt and black pepper. Place pita in the hot skillet and heat until slightly browned. Flip and do the same thing on the opposite side. Remove to a plate and cut the whole pita in half so you have 3 halves of pita.
Meanwhile, whisk together miracle whip and lemon juice and season to taste. Set aside.
Begin layering the sandwich by laying one of the halves of grilled pita on a cutting board. Tear proscuitto slices in half short ways then roll them into loose rolls. Layer the proscuitto rolls and turkey slices evenly across the first half. Spread mayo mixture evenly on another pita half. Place it face down on top of the turkey.
On top of the second pita, layer lettuce, roasted red pepper, tomato, cucumber, and squash. I tried to arrange mine with a clear split in the middle so it would be easy to cut.
Spread mayo on the final pita and place it face down on top of the squash. Grab the biggest chef's knife you have and a friend if you have one close. Have the friend hold each side of the sandwich down while you quickly chop it through the center. Serve with potato chips.