To make the mashed sweet potatoes, peel and cube the potatoes. Add to a large pot and cover with water. Bring to a boil for 20-25 minutes or until tender. Strain the water and transfer to a bowl. Add the remainder of the ingredients and use a potato masher to mash. Set aside.
To make the gravy, melt the ghee over medium heat. Whisk in the arrowroot and cook for 2 minutes. Slowly pour in the chicken cooking broth, constantly whisking. Pour in the remainder of the ingredients and whisk to combine. Allow to simmer for 3-4 minutes or until thick.
Serve the mashed sweet potatoes topped with gravy and additional herbs to serve.