Preheat your oven to 350°F (175°C).
In a mixing bowl, whisk together the sugar and melted vegan butter until well combined.
Add the vegan buttermilk and vanilla extract, and mix well.
In another bowl, sift together the flour, cornstarch, baking powder, and salt.
Gradually add the dry ingredients to the wet ingredients, mixing until just combined.
Pour the mixture into a prepared pie dish.
Bake for 45 minutes, or until the top is golden and a toothpick inserted into the center comes out clean.
Let the pie cool before serving. Enjoy!