1) Boil sweet potato whole in skin for 40 to 50 minutes, or until done. Run cold water over the sweet potatoes, and remove skin.
Break apart potato in a bowl. Add butter, and mix well with mixer. stir in sugar, milk, eggs, nutmeg ,cinnamon and vanilla. Beat on medium speed until mixture is smooth. Pour filling into an unbaked pie crust.
Bake at 350 degrees for 55 to 60 minutes or until knife inserted in center comes out clean. Pie will puff up like soufflé. and then will sink down as it cools.
