FOR THE CUSTARD: In a lg saucepan, bring milk and coffee to slight boil. Quickly whisk in egg/eggwhites, one at a time. Quickly whisk in flour, cornstarch, sugar, and salt; whisking after each addition until well incorporated. Whisk in chocolate.
Boil intermittenly until thick and custard-like in texture. Let cool in a separate bowl until needed.
FOR THE CRUST: Sift together cocoa pwder, confectioners sugar, flour, and salt. Cut in the butter and rub together with fingertips until crumbly. Rub in egg yolk until well-incorporated, kneading until a slight dough forms.
Butter/flour a 9-inch cake pan and press dough into pan to make a crust form. Bake at 350 degrees farenheit for 6-8 minutes (it will darken), scour the bottom with melted chocolate and set aside until needed.
FOR THE MERINGUE: Whip the egg whites until stiff peaks form, slowly incorporate the sugar. Set aside until needed.
ASSEMBLING/BAKING THE PIE: Pour the custard into the crust and top with meringue. Bake at 325 degrees farenheit until meringue is golden at the edges, about 12-20 minutes. Sprinkle with ground coffee and chocolate shavings and refrigerate for at least 8 hours before serving. Eat cold.