Preheat the oven to 400 degrees and place a cast iron skillet inside to heat up for 20 minutes.
Combine all ingredients, except chicken, in a bowl to make a paste.
Add the chicken and massage the paste all over the chicken, getting under the skin if you can without tearing the skin.
Place in the heated cast iron skillet and roast for 30 minutes, or until the internal temperature reads 165 degrees. If the skin is not as crispy as you'd like, pop it under the broiler for a couple minutes to crisp it up.
Garnish with green onions and serve with steamed rice.
Make sure the cast iron skillet is hot before adding your chicken. You want the chicken to brown quickly so the juicy stay inside.
Use room temperature butter to make the miso butter. It is easier to mix when it is softer.
Fresh garlic or roasted garlic can be used in this recipe.
If the skin is not crisp after 30 minutes, place it under the broiler for a couple minutes to crisp it up. Watch it carefully so it doesn't burn.