Slice chicken breasts in half lengthwise to create 4 thin-cut pieces, or use pre-butterflied/thin breasts.
In a large bowl, whisk together pickle juice, milk, powdered sugar, garlic powder, onion powder, salt, pepper, and smoked paprika.
Add chicken to the marinade, ensuring it's coated. Cover with plastic wrap and refrigerate for at least 30 minutes, up to 4 hours.
Preheat griddle over medium heat. Cook bacon until crispy. Set aside.
Cook marinated chicken on the griddle, flipping occasionally, until it reaches an internal temperature of 165°F, about 15 minutes. Toast buns on low heat.
Remove chicken from heat and top each piece with a slice of pepper jack cheese to melt slightly.
To assemble each sandwich, on the bottom bun layer lettuce and a tomato slice. Place a chicken piece over the veggies and top with bacon slices.
Spread Chick Fil A sauce on the top bun and place it on the sandwich.
