Preheat oven to 350°F (175°C).

In a large bowl, mix mashed sweet potatoes, sugar, and butter until smooth.

Add milk, eggs, vanilla, cinnamon, nutmeg, and salt. Mix until well combined.

Pour mixture into the unbaked pie crust.

Bake for 50–60 minutes, or until the center is set and a knife inserted in the middle comes out clean.

Let cool completely before slicing and serving.