Here's a recipe for sweet potato pie:

PREP TIME 30 Min
COOK TIME 1 Hr 50 Min
READY IN 2 Hrs 20 Min
SERVINGS & SCALING
Original recipe yield: 1 - 9 inch pie
US METRIC
      
About scaling and conversions

INGREDIENTS
1 (1 pound) sweet potato
1/2 cup butter, softened
1 cup white sugar
1/2 cup milk
2 eggs
1/2 teaspoon ground nutmeg
1/2 teaspoon ground cinnamon
1 teaspoon vanilla extract
1 (9 inch) unbaked pie crust

DIRECTIONS
Boil sweet potato whole in skin for 40 to 50 minutes, or until done. Run cold water over the sweet potato, and remove the skin.
Break apart sweet 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 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.


http://allrecipes.com/Recipe/Sweet-Potato-Pie-I/Detail.aspx

This page also includes some reviews from folks who used this recipe.


-snip-

I use a recipe for pumpkin pie that I got out of a Betty Crocker cook book and substitute a large can of sweet potatoes {or yams} instead of a can of pumpkin. If you use the canned sweet potatos, empty out the water in the can first before putting the sweet potatos in the mixer.

Fwiw, I use margarine instead of butter. And I don't add vanilla, but I do add clove flavoring with the cinnamon and allspice.