Pull chicken out of the fridge about 20 minutes before roasting.
Preheat oven to 400 degrees.
Remove giblets and pat chicken dry with a paper towel. In a small bowl, mix seasonings. Rub entire chicken with seasonings and mustard.
Cut onion into quarters. Stuff chicken with onion, garlic, lemon, parsley and 2 tablespoon butter. Tie chicken legs together with cooking twine. Cut 1 tablespoon butter into 6 small chunks. Gently slide butter chunks under the top skin layer.
Place chicken on a roasting pan, or on an oven safe rack on a baking sheet. Bake for 25 minutes at 400 degrees. Turn oven down to 350 degrees and bake for an additional 45-65 minutes until internal temperature reaches 165-170 degrees. **During the last 10 minutes baste outside with remaining 1 tablespoon melted butter.
When chicken is finished, remove from oven and let rest for 20 minutes.
Notes
Notes: If the top of the chicken begins to burn before finishing, cover with a piece of foil and continue cooking.