Preheat your oven to 400°F (200°C). Ensure the oven rack is in the middle position.
In a small bowl, combine the softened butter, lemon zest, minced garlic, chopped rosemary, thyme, salt, and black pepper. Mix well to create a compound butter.
Rinse the chicken inside and out and pat it dry with paper towels. Place the chicken in a roasting pan. Loosen the skin over the chicken breast by gently sliding your fingers between the skin and the meat.
Rub the lemon-herb butter mixture under the skin of the chicken breast and over the outside of the chicken. Make sure to evenly distribute the butter for maximum flavor.
Cut the lemon in half and place one half inside the chicken cavity. Add the onion wedges and garlic cloves to the roasting pan around the chicken.
Roast the chicken for about 45 minutes, or until a meat thermometer inserted into the thickest part of the thigh registers 165°F (74°C). If the skin starts to brown too quickly, you can loosely tent the chicken with foil.
Once cooked, remove the chicken from the oven and let it rest for 10 minutes before carving. This allows the juices to redistribute, resulting in a more tender and flavorful chicken.
