Bring a large pot of water to a boil, then add sweet potato slices. Cook until tender, 20-25 minutes. Strain potatoes.
Place potatoes in the bowl of a stand mixer, then mix on medium for 30 seconds using the whisk or paddle attachment. Add butter, one slice at a time, while mixing potatoes on medium speed. Add garlic, then season with salt and pepper. Add a dash or two of chili powder, if desired. Garnish with fresh parsley.
Recipe by sweet caroline's cooking at https://sweetcarolinescooking.com/2014/10/10/third-times-a-charm-savory-mashed-sweet-potatoes/