To make the crust, process the chocolate wafers in a food processor until fine, around 30 seconds. Add the sugar and pulse. Continue pulsing while adding the melted butter. The mixture should look like wet sand.
Evenly press the crumbs into a pie pan, using a measuring cup to press them up the sides.
Put the pie tin on a rimmed baking sheet and place on the middle rack in the preheated oven. Bake for 15-18 minutes. Cool completely on a wire rack.
To make the filling, mix white chocolate chips, milk, half and half, sugar, and flour in a saucepan over medium heat, . Stirring constantly, mix these ingredients until they begin to bubble.
Take a small amount of chocolate mixture and in separate bowl, mix with the egg yolks stirring quickly so the eggs do not cook.
Add the egg mixture to the rest of the chocolate mixture and let it remain on the stove top at a low heat. Add the butter and peppermint extract, stirring until everything is combined.
Take one cup of the hot white chocolate pudding mixture and whisk it together with the semisweet chocolate chips in a separate bowl. Whisk until chocolate melts and the mixture is well combined.
Pour the chocolate mixture into the crust followed by the white chocolate mixture on top. Cover with plastic wrap and refrigerate for about 5 hours or until completely set.
In the bowl of a stand mixer with the whisk attachment, whip the heavy cream, powdered sugar, and peppermint extract on high speed until firm enough to pipe onto pie, about 3-5 minutes. Add to the top of pie as desired. Right before serving, top with crushed peppermint candies (do not add candies too far in advance as they will melt into the pie).