½ (14.1-ounce) package refrigerated piecrusts (1 sheet)
1½ cups sugar
2 large eggs
½ cup whole buttermilk, at room temperature, shaken
¼ cup unsalted butter, melted and slightly cooled
3 tablespoons unsweetened cocoa powder
1 teaspoon vanilla extract
1 cup sweetened whipped cream
Garnish: chocolate shavings
Instructions
Preheat oven to 375°.
On a lightly floured surface, roll piecrust into a 12-inch circle. Transfer to a 9-inch pie plate, pressing into bottom and up sides. Fold edges under, and crimp as desired. Refrigerate 15 minutes. Prick bottom and sides of dough with a fork 10 times.
Bake 10 minutes. Let cool on a wire rack 30 minutes.
In a medium bowl, combine sugar and eggs; beat at medium speed with a mixer until combined. Add buttermilk, melted butter, cocoa, and vanilla, beating until smooth. Pour into prepared piecrust.
Bake until a knife inserted near edge comes out clean, approximately 30 minutes (cover edges with foil to prevent excess browning, if necessary). Let cool completely on a wire rack. Serve with whipped cream. Garnish with chocolate shavings, if desired.