Preheat your oven to 350°F (175°C).
In a large pot, add the cubed purple sweet potatoes and cover them with water. Bring to a boil and cook for 15-20 minutes or until tender. Drain and let cool slightly.
In a mixing bowl, mash the cooked purple sweet potatoes using a potato masher or food processor until smooth.
Add the granulated sugar, vanilla extract, ground cinnamon, ground nutmeg, salt, lemon juice, and eggs to the mashed sweet potatoes. Whisk until well combined.
Gradually stir in the evaporated milk until the filling is smooth and creamy.
Pour the sweet potato filling into the pre-made pie crust, spreading evenly.
Place the pie on a baking sheet to catch any drips, then cover the crust's edges with aluminum foil to prevent over-browning.
Bake in the preheated oven for 45-50 minutes, or until the filling is set and a toothpick inserted in the center comes out clean.
Remove from the oven and let the pie cool completely before serving.
Serve with whipped cream or a scoop of vanilla ice cream for extra indulgence.