Prepare Filling: Combine mashed sweet potatoes, sugars, evaporated milk, eggs, vanilla, cinnamon, nutmeg, and salt until the mixture is smooth and well-combined.
Fill Crust: Pour the prepared sweet potato filling into an unbaked pie crust, spreading it out evenly.
Top Pie: Once the pie has finished baking and cooled slightly, spread the marshmallow whip over the top, covering it completely.
Serve: Slice the pie into portions and serve either warm or chilled, according to preference, for a delightful combination of sweet potato goodness and fluffy marshmallow topping.