Prepare the crust: Mix the chocolate wafer crumbs and melted butter in a medium bowl until evenly moistened. Press the mixture firmly and evenly into the bottom and up the sides of a 9-inch pie plate. Chill the crust in the freezer for 15 minutes while you prepare the filling.
Make the chocolate base: Place the chocolate chips in a heatproof bowl. In a small saucepan, heat the sweetened condensed milk until it just begins to simmer around the edges. Do not boil.
Pour the hot milk over the chocolate chips. Let stand for 5 minutes without stirring.
Add the hot water and vanilla extract to the chocolate mixture. Whisk slowly until the mixture is completely smooth and glossy. This is your high-CPC phrase chocolate base.
Pour the warm chocolate filling into the chilled crust. Smooth the top with a spatula.
Cover the pie loosely with plastic wrap, making sure the wrap does not touch the surface of the filling. Refrigerate for at least 4 hours, or until the filling is fully set.
When ready to serve, spread the thawed whipped topping evenly over the set chocolate filling.
Garnish with chocolate curls or holiday sprinkles. Slice and serve cold.
Notes
For the best make ahead Christmas dessert results, prepare the pie completely (including the whipped topping) one day before serving. Keep it covered in the refrigerator.
If you prefer a homemade whipped cream topping, whip 1 1/2 cups heavy cream with 1/4 cup powdered sugar and 1/2 teaspoon vanilla until stiff peaks form.
If you do not have chocolate wafer crumbs, you can substitute with graham cracker crumbs, but the flavor will change slightly.