If you are baking the crust, preheat the oven to 350 degrees F.
Whip the heavy cream and ¼ cup of the confectioners’ sugar until stiff peaks. Refrigerate until ready to fold into filling.
Process the cookies and sugar until coarse crumbs. Add the butter and pulse until the crumbs and butter are coming together and barely looks dry.
Dump the cookie crumbs into the dish and press the cookies evenly on the bottom and up the sides of the dish. A flat-bottomed glass, a spoon, or your fingers work well.
If you are baking the crust, bake in the preheated oven for 10 minutes, or until lightly browned and smelling fragrant. Remove from the oven to completely cool. If you are not pre-baking the crust, place the newly-pressed crust into the freezer until ready to use.
Place the paddle attachment on a stand mixer. (Alternatively, you can use a hand-held mixer.) In the mixer bowl, add the cream cheese and whip on medium speed until smooth.
Add the peanut butter and whip again on medium until the two ingredients are combined.
Add the remaining cup of confectioner’ sugar, milk, and vanilla. Begin on low speed, gradually working up to medium, whipping the ingredients together until all combined.
Remove the bowl from the stand and fold in the whipped cream. A silicone spatula works very well for this step. Leave some white streaks of whipped cream for aesthetics.
Scrape the filling into the cooled crust. You can either smooth out the top or create peaks with the mixture. Freeze for about 2 hours before gently laying a piece of plastic wrap over the top to finish freezing completely through, about 6 hours.
Make the ganache. In a microwave-safe bowl or 2-cup measuring cup, heat the heavy cream until very hot, but not boiling. Add the chopped chocolate and allow it to stand for 3 minutes.
Stir the mixture until the ganache is smooth. Drizzle the ganache over the frozen pie. It will set fairly quickly because the pie is frozen. If you smoothed out the top of your pie, you can use a spoon or offset metal spatula and smooth out the ganache.
Immediately top with the chopped Reese’s candies so that they can settle into the soft ganache. If you have any ganache left over, you can drizzle over the candies.
The pie should be frozen enough to serve immediately. Or, you can place it back into the freezer to stiffen the ganache.
If serving hours or days later, gently wrap in plastic wrap and then double aluminum foil and place in the freezer.