Preheat oven to 450 degrees F. Mix together the spice blend - herbs de provence, onion powder, garlic powder, cajun seasoning, kosher salt, and black pepper. Add mayo and mix until a paste forms.
Remove insides of chicken and pat dry with a paper towel. Slather the inside of the chicken with some of the mayo mixture. Stuff the cavity of the chicken with half of the celery, yellow onion, carrots, and all of the fresh herbs and lemon slices. Slater the rest of the mayo mixture all around the chicken.
Sprinkle about 1 tbsp of olive oil to the bottom of a large dutch oven or baking dish. Add remaining Celery carrots onion and garlic cloves to the bottom of a cast iron skillet or oven safe braising pan. Place chicken on top. Wrap kitchen twine around the chicken legs and tie together - this ensures that the bird cooks evenly. Roast on the bottom lower rack for 45 minutes.
While the chicken roasting, make the basting juice by melting butter in a skillet over medium heat. Once melted, add garlic to the melted butter and cook for 2-3 minutes, until fragrant. Add a pinch of salt, lemon juice, and parsley. Remove from the stove.
Remove the chicken from the oven and lower oven temperature to 375 degrees F. Use a pastry brush to cover the whole bird in the butter mixture and continue to bake until finished, about 15-25 minutes, until internal temperature reaches 165 degrees F in the thickest part of the thigh and 160 degrees F in the chicken breast. (Note: the size of the chicken will affect how long it takes to reach temperature so keep an eye on your meat thermometer)
Remove from the oven and let the chicken rest for at least 15 minutes prior to cutting.
Optional:add the roasted garlic cloves from the pan and the pan drippings into a food processor and blend until smooth to create a gravy to pour on top of the chicken. If needed, pour into a small saucepan with about a 1/2-1 cup of chicken stock and a cornstarch slurry of 1 tbsp cornstarch and 1 tbsp water. Add to the gravy, mix together, and cook over medium low heat until the gravy thickens.
Bring to Room Temperature: Let the chicken sit out for 30 minutes before cooking to ensure even roasting.
Pat Dry: Use paper towels to thoroughly dry the chicken's skin; this is what gives the chicken that nice crispy skin.
Truss or Tie: Tying the legs together helps the chicken cook evenly and keeps the stuffing in place.
Use an instant read thermometer! It is SO easy to over or undercook chicken. Using a meat thermometer ensures that it's done without having to worry. Once your chicken reads 165 degrees fahrenheit in the chicken thighs and 160 degrees F in the thickest part of the chicken breasts, it's done! Remove from the oven and let it rest.
Rest for 10–15 Minutes: Cover the chicken lightly with foil to let juices redistribute before carving.
Also, you can use this same recipe for your Thanksgiving Turkey just be sure to adjust for cooking time.