Preheat the oven to 500 degrees. Mix the butter, herbs, and spices to create a compound butter mixture.
Remove giblets from chicken and set aside or freeze to use for stock later. Rinse the chicken and pat it dry with a paper towel.
Using your fingers or a spatula gently loosen the skin from the meat starting at the back end. Be very careful to not tear the skin. Once you have loosened the skin take half of the butter mixture and work it across the breast under the skin.
Use the remaining butter mixture and rub it over the body of the chicken covering all of the surface area. Place chicken into cast iron skillet or roasting pan.
Place the sprigs of rosemary and thyme into the cavity along with the slices of one lemon and 1/4 of the onion.
Take the remaining onion and carrots and arrange around the chicken. Place the slices of the remaining lemon over the the vegetables.
Cook chicken at 500 degrees for 20 minutes to help the skin brown. Then turn heat down to 350 degrees and continue to cook for another 45 minutes or until the chicken has reached at least 170 degrees all over. If it over browning but not yet cooked through, cover the breast with tinfoil loosely. Let rest for 10 minutes and then serve!
If you are on a Whole30 substitute the butter with ghee or olive oil in an equal amount.