Position oven rack in bottom third of oven. Preheat oven to 400°F (200°C).

On a lightly floured surface, roll All-Butter Pie Dough into a 12-inch circle (about ⅛ inch thick). Transfer to a 9-inch pie pan, pressing into bottom and up sides. Trim excess dough to ½ inch beyond edge of pan, if needed. Fold edges under, and crimp as desired. Freeze until firm, about 15 minutes.

In a large bowl, whisk together sugar, flour, and salt. Whisk in eggs, melted butter, and 1 teaspoon (4 grams) vanilla until combined. Whisk in buttermilk. Stir in chopped coconut. Pour into prepared crust.

Bake for 18 to 20 minutes. Loosely cover with foil, and reduce oven temperature to 350°F (180°C); bake until edges are set but center still has a slight jiggle and an instant-read thermometer inserted in center registers 200°F (93°C), 40 to 45 minutes more. (The pie may puff when removed from the oven and then deflate slightly as it cools.) Let cool completely on a wire rack. Refrigerate until ready to serve.

Just before serving, in a medium bowl, whisk together cold cream and remaining ½ teaspoon (2 grams) vanilla until thickened and medium-stiff peaks form.

Spoon onto pie, and garnish with toasted coconut, if desired. Refrigerate in an airtight container for up to 3 days.