One to two days before cooking, place the chicken in a baking dish. Using your fingers, gently loosen the skin from the breasts and thighs without breaking the skin. Carefully slide the sprigs of thyme and the garlic under the skin. Put the lemon in the cavity. Tie the legs together and tuck the wings under the body. Sprinkle with 2 teaspoons of sea salt and the pepper, cover the dish tightly with plastic wrap, and refrigerate for 24 to 48 hours
The day of, preheat the oven to 500 degrees. Place the bread in a medium (10-12 inch) cast-iron skillet in a single layer. Brush the chicken with olive oil and place it, breast side up, on top of the bread.
Roast for 30 minutes, turn it over and roast for 15-20 minutes, until the juices run clear when you cut between the leg and the thigh and the internal temperature reads 175 degrees.
Remove from the oven and wrap the skillet tightly with aluminum foil.
Allow the chicken to rest at room temperature for a full 30 minutes.
Carve and place on a serving platter or store in airtight containers or storage bags.
