Combine ingredients. In a mixing bowl, gently mix together the ground chicken, chopped bacon, diced red onion, minced garlic, grated apple, apple juice, dried sage, panko bread crumbs, salt, and pepper.

Shape patties. Form the mixture into 6 evenly sized patties, about ¾ inch thick.

Cook patties. Preheat a skillet or grill over medium heat. Cook the patties for about 6-8 minutes on each side, or until they reach an internal temperature of 165°F and are golden brown.

Make the sauce. In a separate bowl, whisk together Dijon mustard, maple syrup, and mayonnaise until smooth.

Toast buns. Lightly toast the brioche buns in a skillet or oven until golden brown.

Assemble burgers. Layer the cooked chicken apple patty on the bottom half of the brioche bun, followed by Monterey Jack cheese, sauce, fresh lettuce, and parsley.