Preheat oven to 350℉. Whisk together all ingredients except for chicken. Set aside. Rinse chicken and pat dry with a paper towel. Place chicken in a large casserole dish or roaster. Spread 3/4 of mustard mixture evenly over entire chicken.
Roast uncovered in preheated oven for 60 minutes. Brush chicken with remaining mustard coating and continue to roast for an additional 45-60 minutes or until an instant read thermometer registers 170℉ at the thickest part of the thigh. Remove from oven and cover with foil and allow to rest for 15-20 minutes. Cut chicken into pieces and serve immediately.
If using as a one pan meal, add evenly cut potatoes and other vegetables along with fresh herbs to the roasting pan after the chicken has cooked for 30 minutes. Turn vegetables when you brush the chicken with remaining mustard rub.
Roasting time will vary depending on the size of your chicken.