How to Make It
Combine granulated sugar and flour in a heavy saucepan. Whisk together milk and egg yolks. Gradually whisk egg mixture into sugar mixture; bring to a boil over medium heat, whisking constantly. Boil 3 minutes or until thickened; remove from heat.
Stir in butter, 1 cup coconut, and 1⁄2 tsp. vanilla. Cover with plastic wrap, placing plastic wrap directly on surface of filling in pan; let stand 30 minutes. Spoon custard into prepared crust; cover and chill 30 minutes or until set.
Meanwhile, beat whipping cream at high speed with an electric mixer until foamy; gradually add powdered sugar and remaining 1⁄2 tsp. vanilla, beating until soft peaks form. Spread or pipe whipped cream over pie filling. Store in refrigerator. Garnish, if desired.