Preheat the oven/grill to 325°.
In a mixing bowl, add sugar, eggs, flour, and vanilla.
Mix those ingredients well.
Add in the butter, about 2/3 of the coconut flakes (reserve the rest for the top), and buttermilk.
Once ingredients are well combined, pour into pie crust and sprinkle the remaining coconut flakes on top.
Bake pie for 1 hour or until golden brown.
Cool before serving.