FILLING: Combine milk and 2 cups sweetened coconut in a 3 1/2-quart saucepan. Split vanilla bean in half lengthwise, and scrape seeds into milk mixture. Add pod. Cook over medium-high heat, stirring occasionally, until mixture almost comes to a boil. Remove from heat.
Whisk together eggs, 1/2 cup plus 2 tablespoons sugar, and flour in a medium bowl until well blended. Gradually whisk about 1/3 cup milk mixture into egg mixture; pour back into saucepan. Cook over medium heat, whisking constantly, 6 minutes or until mixture thickens and begins to bubble. Whisk 3 more minutes or until very thick. Remove from heat; add butter, and whisk until melted. Discard vanilla pod. Transfer mixture to a medium bowl, and place entire bowl in a larger bowl of ice water. Stir occasionally until mixture cools. Remove medium bowl from ice bath, and place plastic wrap directly on surface of mixture; chill 4 hours or until cold. (Mixture will thicken.).
CRUST:Pulse first 5 ingredients in a food processor 6 to 10 times or until mixture is crumbly. Add water, 1 tablespoon at a time, pulsing once after each addition, until dough holds together when pressed between fingers. (Dough will not form a ball or even clump together in processor—it will be loose.).
Turn dough out onto a large sheet of plastic wrap; press into a disc. Cover with plastic wrap, and chill 1 hour.
Roll dough to a 12- to 13-inch circle on a lightly floured surface. Fit into a 9-inch pie plate, trimming excess to a 1- to 11/2-inch overhang. Turn dough under along rim of pie pan, and flute edges. Chill at least 1 hour before baking.
Preheat oven to 400°. Place a sheet of aluminum foil or parchment paper in piecrust, extending over edges, and fill with dried beans, rice, or pie weights. Bake at 400° for 20 minutes. Remove from oven; discard foil and beans, and return piecrust to oven. Bake for 14 to 17 more minutes or until edges are golden brown. Remove from oven, and cool completely on a wire rack.
TOPPING: Fill baked Coconut Piecrust with pastry cream, smoothing surface. Beat whipping cream, remaining 1/4 cup sugar, and vanilla extract at medium speed with an electric mixer until foamy. Gradually increase speed to high, and beat until soft peaks form. Pipe or spoon whipped cream over pie.
Preheat oven to 350°. Spread coconut chips on a baking sheet, and bake at 350° for 7 to 8 minutes or until golden, stirring twice. Cool. Top pie with coconut, and garnish, if desired.