1. Remove the backbone and butterfly the chicken. If the pan isn't big enough, cut the chicken into 2 halves.
2. In a bowl, mix together the rosemary, thyme, some salt, garlic, mustard and 1 tbsp. of the olive oil.
3. Rub mixture all over chicken.
4. Preheat oven to 450 degrees F.
5. Heat the remaining 1 tbsp. olive oil in a 9-inch cast iron skillet over medium-high heat until oil is shimmering.
6. Put the chicken in the pan, skin-side down.
7. Weight the chicken with another ovenproof skillet or flat pot and put some bricks on top. (Make sure the chicken is weighted evenly).
8. Cook over medium-high heat for 10 minutes.
9. Carefully transfer to the oven.
10. Roast the chicken for 15 minutes.
11. Carefully remove from the oven and remove the weights.
12. Flip chicken over and roast for 10 minutes more or until the chicken reaches an internal temperature of 175 to 180 degrees F and the juices run clear.
13. Serve with the lemon wedges and the pan juices.