Mix the garlic, Herbes de Provence, Dijon mustard, avocado oil, pomegranate molasses, and serrano pepper in a bowl.
Lightly season with salt and cover the chicken with the mixture. Make sure to get some under the skin.
Heat your cast iron skillet on the stove. Add a thin layer of oil, if necessary*. Place the chicken skin side up in the pan. If you have any marinade left in the bowl, add the remaining mixture on top of the chicken. Cook 5 minutes until starts to brown. Transfer to the oven.
Cook 25-30 minutes in the oven until internal temperature reads 155F.* It will continue to cook while it rests. Let rest 5 minutes before serving.
Notes
*If your pan is well seasoned you may not need additional oil. Buying store-bought pomegranate molasses is usually less expensive than making your own.