Spray a 10" springform pan with cooking spray. Wrap the outside sides and bottom of the pan in two layers of aluminum foil.
In a small bowl, combine the crushed Oreos and melted butter. Press this mixture into the bottom of the prepared springform pan. Set aside.
Preheat the oven to 350 degrees.
In a large bowl, combine cream cheese, sugar, and peanut butter. Add the eggs, one at a time, beating after each addition. Be careful not to overbeat the mixture. Just mix until each egg is combined.
Add the sour cream and lemon juice. Mix just until everything is blended. Pour the cheesecake mixture into the Oreo crust. Use the back of a spoon to smooth and spread the filling. This will help release any air bubbles.
To prepare the hot water bath, place the springform pan into a larger cake or roasting pan. Boil 1-2 quarts of water. Pour the boiling water into the larger pan until the water comes about halfway up the side of the foil covered springform pan.
Place the pans of cheesecake in the center of middle oven rack. Bake 15 minutes, then lower the oven temperature to 300 degrees and bake another 50 minutes or until set. The edges should be light brown. There shouldn't be any liquidy spots in the center of the cheesecake. Be careful not to bake too long. The cheesecake will continue to cook after it is removed from the oven. Remove the springform pan from the hot water bath. Place it on a wire rack with a towel underneath to soak up any extra drips of water. Allow the cheesecake to cool completely.
While the cheesecake is cooling, prepare the ganache. Place the chocolate chips and heavy cream in a microwave safe bowl. Melt the chocolate chips in 20-30 second intervals, stirring between each interval. Do this until the chocolate is completely melted and smooth, being careful to not let the chocolate get too hot. Allow the ganache to sit for 3-4 minutes, then spoon it on top of the cheesecake. Spread the chocolate just to the edges of the cheesecake.
Once the cheesecake has cooled to room temperature, place it in the refrigerator. Allow the cheesecake to set overnight in the fridge before serving.
If desired, you can decorate the top with peanut butter frosting and buttercream.
For the peanut butter frosting: In a bowl, blend together peanut butter, powdered sugar, butter, and milk 3-4 minutes or until light and fluffy. Use an icing bag and tip 1M to pipe starts around the edges of the cheesecake. Place buckeye on each slice of cheesecake.