I found this recipe online and made a few changes. I am not crazy about sweet potatoes but this pie is pretty tasty and was a hit with my family. I used a pre-made graham cracker crust.

For the Filling:

3 pounds medium red-skinned sweet potatoes (yams)
14-ounce can sweetened condensed milk
1/4 cup sugar
2 large eggs
2 teaspoons lemon juice
1 teaspoon ground cinnamon
1/2 teaspoon ground nutmeg
1/4 teaspoon salt

For the Marshmellow Topping:

7-ounce jar Kraft Jet-Puffed Marshmallow Creme
4 ounces of Kraft Cool Whip

Directions:

For Filling: Preheat  oven to 350°F. Pierce sweet potatoes all over with fork; place potatoes on  rimmed baking sheet. Bake until potatoes are very tender when pierced with fork,  about 1 hour 15 minutes or you can boil your potatoes for 40 to 50 minutes. If you boil the potatoes, run under cold water and peel. If you bake them, let them cool and cut potatoes open and scoop out pulp.  Transfer pulp to processor and puree until smooth. Preheat oven to 350°F.  Combine 2 cups sweet potato puree, sweetened condensed milk, eggs, lemon juice, cinnamon, nutmeg and salt in a large bowl; whisk until well blended and smooth. Pour filling into crust. Bake pie until puffed around edges and set in center, about 40 to 50  minutes. Transfer pie to rack and cool. Refrigerate pie.