Follow these steps carefully for pie perfection:

Step 1: Prepare the Chocolate Cookie Crust

1. Place the whole Oreo cookies (filling and all) into a food processor. Pulse until they are fine crumbs. If you don’t have a food processor, place them in a sturdy zip-top bag and crush them with a rolling pin.
2. Transfer the crumbs to a medium bowl. Pour the melted butter over the crumbs and stir with a fork until all the crumbs are moistened and resemble wet sand.
3. Press the crumb mixture firmly and evenly into the bottom and up the sides of a 9-inch pie dish. Use the bottom of a glass or measuring cup to help create a compact, even layer.
4. Chill the crust in the refrigerator for at least 30 minutes (or freeze for 15 minutes) while you prepare the filling. This helps it set and prevents it from crumbling when you add the filling.

Step 2: Make the Creamy Peanut Butter Filling

1. In a large bowl, using an electric hand mixer or a stand mixer fitted with the paddle attachment, beat the softened cream cheese on medium speed until completely smooth and creamy, about 1-2 minutes. Scrape down the sides of the bowl.
2. Add the creamy peanut butter and powdered sugar to the bowl with the cream cheese. Beat on low speed initially to combine, then increase to medium speed and beat until well-combined, smooth, and fluffy, about 2-3 minutes. Scrape down the sides of the bowl again.
3. Stir in the vanilla extract.
4. In a separate, clean, chilled bowl, pour in the cold heavy whipping cream. Using clean beaters (or a whisk attachment for a stand mixer), whip the cream on medium-high speed until stiff peaks form. Stiff peaks mean that when you lift the beaters, the cream holds its shape and the peak points straight up or curls over slightly without collapsing. Be careful not to over-whip, or it will turn into butter.
5. Gently fold about one-third of the whipped cream into the peanut butter mixture using a spatula to lighten it. Then, add the remaining whipped cream and fold carefully until just combined and no white streaks remain. Avoid overmixing, as this will deflate the whipped cream. (If using Cool Whip, simply fold it into the peanut butter mixture until combined).

Step 3: Assemble the Pie

1. Retrieve the chilled crust from the refrigerator.
2. Spoon the peanut butter filling into the prepared crust, spreading it evenly with a spatula or the back of a spoon. Smooth the top as much as possible.
3. Cover the pie loosely with plastic wrap (try not to let it touch the filling) and refrigerate for at least 4-6 hours, or preferably overnight, until the filling is firm and well-chilled. This chilling time is crucial for the pie to set properly and for the flavors to meld.

Step 4: Prepare the Chocolate Ganache Topping

1. Once the pie filling is firm, prepare the ganache. Place the semi-sweet chocolate chips or chopped chocolate in a heatproof bowl.
2. Heat the heavy whipping cream in a small saucepan over medium heat until it just begins to simmer around the edges (do not let it come to a rolling boil).
3. Pour the hot cream directly over the chocolate in the bowl. Let it sit undisturbed for 5 minutes. This allows the hot cream to melt the chocolate.
4. After 5 minutes, gently whisk the mixture, starting from the center and working your way out, until the ganache is smooth, glossy, and completely combined. If there are still a few unmelted chocolate bits, you can microwave the mixture in 10-second intervals, whisking in between, until smooth – be very careful not to overheat, or the chocolate will seize.
5. Let the ganache cool slightly at room temperature for about 10-15 minutes, whisking occasionally. It should still be pourable but not hot, as hot ganache could melt the peanut butter filling.

Step 5: Top and Chill the Pie

1. Pour the slightly cooled ganache over the chilled peanut butter pie. Use a spatula to gently spread it evenly over the top, allowing some to drizzle down the sides if desired.
2. If using, immediately sprinkle on any optional garnishes like chopped peanut butter cups, roasted peanuts, or chocolate shavings while the ganache is still wet, so they adhere.
3. Return the pie to the refrigerator and chill for at least another 1-2 hours, or until the ganache is set.