01 - In a medium bowl, whisk together the maple syrup, Dijon mustard, olive oil, apple cider vinegar, minced garlic, thyme, salt, and black pepper until smooth and well combined.
02 - Place the chicken breasts in a large resealable bag or shallow dish. Pour the marinade over the chicken, ensuring all pieces are evenly coated. Seal or cover and refrigerate for at least 1 hour, or up to 8 hours for more pronounced flavor.
03 - Preheat your grill to medium-high heat (approximately 375–400°F). Lightly oil the grill grates to prevent sticking.
04 - Remove the chicken from the marinade, shaking off any excess. Discard the remaining marinade. Place the chicken on the grill and cook for 5–7 minutes per side, or until the internal temperature reaches 165°F when checked with a meat thermometer.
05 - Transfer the chicken from the grill to a plate or cutting board and let it rest for 5 minutes before slicing. Garnish with chopped fresh parsley and serve with lemon wedges alongside grilled vegetables or a crisp green salad.