Buttermilk Chocolate Chess Pie

Ingredients

• 1 1/2 cups sugar
• 3 1/2 tablespoons unsweetened cocoa powder
• 1 tablespoon all-purpose flour
• 3 large eggs, beaten
• 1/4 cup butter, melted
• 1 tablespoon vanilla extract
• 1/2 cup buttermilk
• 1 pie crust, 9-inch
• powdered sugar to dust on top