Preheat the oven.
Preheat your oven to 350°F (175°C).
Prepare the Okinawan sweet potatoes:
Peel and cut the Okinawan sweet potatoes into chunks. Boil them in water until they are soft, about 15-20 minutes.
Drain the water and mash the sweet potatoes until smooth. You should have about 2 cups of mashed sweet potatoes.
Make the filling:
In a large bowl, combine the mashed sweet potatoes, coconut milk, sugar, melted butter, beaten eggs, vanilla extract, cinnamon, nutmeg, and salt. Ensure that you thoroughly combine all the ingredients.
Assemble the Pie:
Pour the sweet potato mixture into the unbaked pie crust, spreading it out evenly.
Bake the pie:
Bake the pie in the preheated oven for 50-60 minutes, or until the filling sets and the crust turns golden brown. A toothpick inserted into the center should come out clean.
Cool and Serve:
Allow the pie to cool to room temperature before slicing. You can serve it as-is, with a dollop of whipped cream, or with a scoop of vanilla ice cream.