Mash Herbes de Provence into the softened butter until well blended to create a compound butter.

Rinse the whole chicken inside and out with cold water and pat dry with paper towels to ensure even cooking and crispy skin.

Soak the clay pot and its lid in cold water for 15 minutes to prevent cracking during the roasting process.

Place half of a lemon inside the chicken's cavity to infuse it with flavor.

Truss the chicken with kitchen twine to maintain its shape during cooking. Fold the wings under for even cooking.

Rub the herb butter mixture evenly over the entire surface of the chicken, ensuring it is well coated.

Sprinkle the chicken generously with salt and pepper to taste.

Slice the remaining half of the lemon into 3 or 4 slices.

After soaking the clay pot, line the bottom evenly with the prepared onion wedges, celery pieces, carrot pieces, whole garlic cloves, and lemon slices.

Place the chicken, breast side up, on top of the vegetable base in the clay pot.

Pour the chicken broth (or white wine) over the chicken, adding moisture and flavor to the dish.

Cover the pot tightly with the soaked clay pot lid.

Place the clay pot into a COLD oven to prevent thermal shock, then set the heat to 450°F.

Cook for 1 hour and 15 minutes, or until the chicken legs move easily and the skin is nicely browned. Check for doneness using a meat thermometer, aiming for an internal temperature of 165°F.

For crisper skin, remove the lid during the last 10 minutes of cooking.

Carefully transfer the roasted chicken to a serving platter.

Let the chicken rest for 10 minutes before carving to allow the juices to redistribute, resulting in a more moist and tender bird.

Carve the chicken and serve with the pan juices and roasted vegetables, if desired.