Boil six cups of water in a large pot over high heat then add in the sweet potatoes and boil for about 25 minutes or until completely soft in the center.

Remove the sweet potatoes from the pot and let them cool for about 30 minutes or until you can handle them easily.

Preheat the oven to 375 degrees F.

Remove the peels from the sweet potatoes then add them to a large food processor and blend until almost smooth.

Add in the butter and blend until completely smooth.

Press the pie crust into a pie pan and crimp the edges in a design that you like then poke the bottom of the crust five to six times with a fork.

Measure out two cups of the sweet potato puree and add it to a large mixing bowl along with the evaporated milk, brown sugar and eggs and whisk until completely combined.

Stir in the cornstarch, cinnamon and salt then pour the entire mixture into the pie crust.

Bake for 35-45 minutes or until the center of the pie is set and jiggles only slightly when you move it.

Let it cool for one hour before slicing and serving with whip topping if desired.