Begin by making the herb butter. Add the butter, parsley, sage and thyme into a bowl along with the finely chopped garlic. Mix everything to combine and set aside. You will use this mixture to rub underneath and on top of the chicken skin.
Preheat oven to 400°F.
Remove the chicken from the packaging. Remove the giblets from the cavity (if they are included) and pat the outside of the chicken dry using a paper towel.
Get ready to stuff the bird by placing the chicken into a roasting dish. Prop the chicken up and season the cavity lightly with salt and pepper mixture. Next, cut 1 onion into quarters and stuff them into the cavity of the chicken along with the remaining 3 whole cloves of garlic.
Lay the chicken back down into the roasting pan, breast side up. Using your fingers, begin to separate the skin of the chicken from the breast and legs by running your fingers underneath the skin and gently pulling upwards. Try not to tear the skin.
Next, place tablespoon-sized balls of butter underneath the skin of the chicken, distributing it evenly across both on the breasts and the legs. I find it easiest to add dollops of the butter underneath the skin first then massage the butter across the breasts and legs by pressing on the top of the skin. If you use your hands to spread the butter underneath the skin, the moisture of the chicken makes it much harder and it tends to clump up.
Rub any the remaining butter mixture from your hands over the skin of the chicken. Make sure you rub the legs, wings and underside of the chicken as well as the breasts. F
Wash your hands and then sprinkle with salt and pepper, and a drizzle of olive oil. Make sure to rub the olive oil evenly across the skin so that it gets nice and crisp.
To ensure that the chicken cooks evenly, truss the legs together. Simply use butchers twine to tie the legs together. It doesn't have to be too tight, just make sure the legs won't separate. Additionally, to ensure the wings don't overcook, simply tuck them underneath the chicken, no trussing required.
Scatter the remaining onion and chopped carrots on the bottom of the roasting dish and set the chicken on top.
Bake the chicken in the center of the oven for 45 minutes. After 45 minutes, flip the chicken on its back and roast for another 15 minutes. After these 15 minutes, flip the chicken back to breast-side up and roast for another 15 minutes. Remove from the oven once the temperature reaches 160 degrees F. Then, cover the chicken with aluminum foil and let it rest for at least 15 minutes before serving. Resting will continue to cook the chicken to its perfect doneness at 165 degrees F and will make it nice a juicy.