I made this pie for my husband for our anniversary. He ate sweet potatoe pie all the time when he was in the army. I decided to surprise him and make it. He said that it was the best one he had ever eaten. He then had another slice, a big slice.
Open can and pour out the liquid in the can with the sweet potato. Add sweet potato to bowl and break up.
Add butter, and mix well with mixer. Stir in sugar, milk, eggs, nutmeg, cinnamon, flour and vanilla. Beat on medium speed until mixture is smooth. Pour filling into an unbaked pie crust.
Bake at 350 degrees F (175 degrees C) for 55 to 60 minutes, or until knife inserted in center comes out clean. Pie will puff up like a souffle, and then will sink down as it cools.