Reserve 4 tablespoons of sauce and then pour the remaining honey mustard mixture over the chicken, toss and cover with plastic wrap and let it sit for about 30-45 minutes at room temperature.
Preheat the grill on medium-medium high heat, grill chicken for about 6 to 7 minutes per side or until chicken is done.
Pour the reserved honey-mustard sauce over chicken and let rest under foil for about 5 minutes. Serve.
Notes
Do not use marinade that has touched the raw chicken to put on top of the cooked chicken. This will cause food poisoning. Make sure to reserve some of the marinate at the beginning.