Wash the skin of the sweet potatoes and add them to a large pot. Cover with cold water and bring to a boil. Boil until a fork or knife inserted in the center goes through with no resistance--about 30 to 40 minutes.
Transfer the potatoes to a bowl to cool. When cool, peel off the skins and remove any eyes or dark spots.
Preheat your oven to 350.
Fit your pie crust to a 9-inch pie plate and flute or decorate the edges as desired. Set aside.
With a hand mixer or in the bowl of a stand mixer, mash the potatoes until smooth. Add all of the remaining ingredients and blend to combine.
Pour the sweet potato mixture into the pie shell and bake, until the center jiggles but is just firm to the touch--about 50 to 55 minutes. Tent the pie with foil if it starts to get too dark.
Remove from the oven and allow the pie to cool about an hour. Cover with plastic wrap and chill until firm and set--about 3 hours or overnight. Serve with whipped cream and a sprinkle of cinnamon.