In a medium bowl, whisk together the Nate's honey, Dijon mustard, olive oil, lemon juice, minced garlic, paprika, rosemary, salt, pepper, and cayenne (if using) until well combined.
Place the chicken in a large zip-top bag or a shallow dish. Pour about 3/4 of the honey mustard marinade over the chicken, reserving the remaining marinade for basting later. Seal the bag or cover the dish and refrigerate for at least 30 minutes, or up to 4 hours, to allow the flavors to meld.
Preheat your grill to medium-high heat. Lightly oil the grill grates to prevent sticking.
Remove the chicken from the marinade, letting any excess drip off. Discard the used marinade. Place the chicken on the preheated grill.
Grill for 6-8 minutes per side (for breasts) or 8-10 minutes per side (for thighs), or until the internal temperature reaches 165°F. During the last few minutes of grilling, baste the chicken with the reserved fresh honey mustard marinade. This creates that beautiful, sticky glaze!
Once cooked through, remove the chicken from the grill and let it rest for 5 minutes before slicing and serving.