Preheat your oven to 350°F (175°C).
Wash and peel the sweet potatoes, then boil them until tender.
Drain and mash the sweet potatoes in a large bowl.
Add sugar, milk, and heavy cream to the mashed sweet potatoes.
Beat in the eggs and vanilla extract until well combined.
Sprinkle cinnamon, nutmeg, and salt into the mixture and stir.
Pour the filling into the pre-made pie crust.
Bake in the preheated oven for 45-50 minutes, or until set.
Remove from the oven and let it cool on a wire rack.
Serve warm or chilled, topped with whipped cream if desired.