• Preheat your oven to 300 degrees Fahrenheit (150 degrees Celsius) and line a 9-inch springform pan with a large sheet of parchment paper.
• Put your oreo cookies in a food processor and process until you get crumbs. You can also crumble them by hand in a Ziploc bag, crushing them with a rolling pin. Mix with the melted butter.
• Press the base mixture in the bottom of the pan and bake for 15 minutes.
• Add the room temperature cream cheese to a large bowl and mix well with a hand mixer until creamy and smooth (you can also use a stand mixer fitted with a paddle attachment).
• Add the sugar, room temperature sour cream, cocoa powder and vanilla and mix well.
• Melt the chocolate, cool it so it's barely warm, and add in a slow, continuous stream to the cheesecake mixture while mixing.
• Add the room temperature eggs one at a time, slowly mixing and scraping down the sides of the bowl after each addition. Mix well, but don't over-mix or whip the batter. This will create large air bubbles in the batter which can cause cracking and an uneven texture.
• Pour the batter into the line springform pan and bang the pan on the countertop to encourage any bubbles to come to the top.
• Place the pan in the oven and bake for an hour until the cheesecake is set around the edges but jiggly in the middle.
• When the cheesecake is done, prop the oven door open with a wooden spoon and let it cool for 2 hours.
• Place the cheesecake in the fridge, uncovered, to chill for at least 2 hours or overnight.

For the ganache:

• Before serving, heat up the cream until it's hot but don't boil it. Add the chocolate in small chunks and cover for a couple of minutes to allow to melt. Mix well.
• Remove the cheesecake from the pan and spread the chocolate ganache all the way to the edge, pushing it a little so it starts dripping down the sides a bit.
• Return to the fridge for 20-30 more minutes to set the ganache.
• Slice and serve with some fresh berries, chocolate whipped cream, shaved chocolate, or all on its own.