Crust:

1. Adjust the oven racks so one is in the lowest position and the other is in the middle position.  Preheat the oven to 350°F.  Use a food processor to grind the whole Oreo cookies into fine crumbs.
2. In a medium bowl, whisk together the Oreo cookie crumbs, sugar, and salt.  Add in the melted butter and stir to evenly moisten the mixture.  It should look like wet sand.
3. Press the crumbs into the bottom and partially up the sides of a 9″ springform pan.  (No need to grease the pan.)  Use the bottom of a glass or measuring cup to help compact the crust down tightly.
4. Bake the crust for 8 minutes on the middle rack.  Remove from the oven and allow to cool slightly while you prepare the filling.

Cheesecake Filling:

1. Lower the over temperature to 325°F.  Have a large roasting pan nearby and begin to boil ~5-6 cups of water.  This pan will be filled with hot water and placed on the lower rack of the oven to create steam while the cheesecake bakes (in place of a traditional water bath).
2. It’s important to have all filling ingredients at room temperature before beginning!  Start by adding the cream cheese, sugar, cornstarch and salt to the bowl of a stand mixer fitted with the paddle attachment.  Beat together on a medium-low speed until smooth and creamy, scraping down the sides and bottom of the bowl as needed.
3. Mix in the eggs, one at a time until just incorporated.  Mix in the peanut butter and vanilla.  Lastly, add in the sour cream on a low speed until evenly combined.
4. Pour the batter into the cooled cookie crust and give the pan a gentle shake to even out the top.  (Or use a small offset spatula to smooth the top.)
5. Place the large roasting pan on the lowest oven rack and fill with the boiling water.  Place the cheesecake above the center of the roasting pan on the middle oven rack.
6. Bake for 60-70 minutes.  The cheesecake is done when the edges are slightly puffed up and the center is almost set.  The center should jiggle like jello when the pan is lightly shaken.
7. Turn off the oven and crack open the oven door slightly, but leave the cheesecake inside.  Let it cool in the oven for 1 hour.  Then remove from the oven and let the cheesecake sit at room temperature for 30 minutes before transferring to the fridge for 4 hours or overnight.
8. After chilling, run a sharp small knife between the edge of the pan and the side of the cheesecake to loosen.  Then remove the side of the springform pan.

Topping:

1. Add the chopped chocolate to a medium size bowl.  Heat the heavy cream until simmering and then pour over the chocolate.  Let sit for 3 minutes to begin melting.  Stir to fully melt the chocolate until the ganache is smooth.
2. Pour ganache over the top of the cooled cheesecake.  If desired, add chopped peanut butter cups to the top of cheesecake for added decoration.