Place herbs under the skin of the breast of the chicken. Rub the chickens with olive oil and marinate covered in the refrigerator for at least 1 hour. Preheat oven to 450 degrees F. Truss the chickens and season with salt and pepper to taste.
Place the chickens on a rack and roast for 15 minutes. Reduce heat to 350 and continue roasting for 35 to 40 minutes.
Remove from oven and let rest.
Place orange juice in a medium saucepan and cook over high heat until reduced to a thick caramelized syrup.
Place chicken stock in a medium saucepan and cook until reduced by 3/
Add the stock to the orange juice and cook for 5 minutes.
Whisk in butter and pepper. Season with salt to taste.
Place all ingredients in a food processor and process until smooth. Fold the puree into the mashed potatoes and season with salt and pepper to taste.