Place both flours and cocoa in bowl of electric mixer fitted with paddle attachment. Add chilled butter cubes. Combine water and salt. Add to flour/butter mixture. Blend on low speed until the mixture resembles a "shaggy" mess. 

Remove mixture from bowl and roll on lightly floured  surface into a 1/2-inch thick rectangle. Do a four fold, turn dough, roll again and do another four fold. Refrigerate dough 30 min.

Repeat above rolling with two more four folds. Cover and refrigerate at least 1 hour before rolling to use.

To use, roll dough to 1/8-inch thickness. Use a 4-1/2-inch round cutter to make 29 dough circles. Chill dough circles , if needed, before filling and baking. (NOTE: Yield is based on using all of the dough, including rerolling the scraps, so handle the scraps carefully.)

Meanwhile, combine pastry cream and OREO Small Cookie Pieces. Set aside until ready to use.

Place 1 oz. of filling in center of each dough circle. Use a light amount of egg wash on the edge of half of the dough circle. Fold dough over filling pressing to adhere to egg wash. Refrigerate.

When ready to bake, brush lightly with egg wash. Poke a few holes in the top center of each for venting. Bake in preheated 400ºF oven 25 to 35 min. or until dough is completely dry. 

Melt white coating chocolate and stripe over each hand held pie. Sprinkle with some of the OREO Medium Cookie Pieces. Let coating set, then serve. Best served the day they are made.