Preheat oven to 350 degrees. Spray 9-inch pie pan with non-stick cooking spray.
In a medium-sized mixing bowl, mix cream cheese and butter until combined. Add in flour and mix until the dough starts to clump together. If necessary, knead together to form a ball, and then press the dough down into the pie pan, covering the bottom and the sides of the pan.
Peel the sweet potatoes and cut up into one-inch chunks. Place in a pot with boiling water just covering the potatoes, and cook until fork-tender. Puree the cooked sweet potatoes in a food processor to get smooth consistency.
In a large mixing bowl, combine mashed sweet potatoes and remaining ingredients, and stir to incorporate. Pour into pie shell, and bake for 60 minutes.
Allow pie to cool, and serve topped with whipped cream.
To make the mashed sweet potatoes from scratch: Use one pound of sweet potatoes, which will be 3-4 small potatoes. Peel the potatoes. Add them to a pot of boiling salted water. Bring it back to a boil, then lower heat and simmer for 15-20 minutes, until fork tender. Drain, cool, and mash the potatoes. Alternatively, you can use precooked refrigerated mashed potatoes or canned sweet potatoes (without additional ingredients).