Melt the chocolate and prepare the crustSpray the bottom and sides of an 8" or 9" springform pan with cooking spray. Add a parchment paper circle to the bottom of the pan (it doesn't need to come up the sides) and spray the parchment lightly. Set aside.

Break up the semisweet chocolate and place it in a heatproof bowl. Set the bowl over a pan of barely simmering water.

Heat the chocolate until it is completely melted and smooth, stirring occasionally. Once melted, remove the bowl from the heat and allow the chocolate to cool slightly.

In the bowl of a food processor, process the Oreos into large crumbs. 

Pour the melted butter over the crumbs and process until the mixture is evenly moistened and the cookie crumbs are ground fine.

Next, pour the crumb mixture into the springform pan and press the crumbs down into an even layer. Use the bottom of a drinking glass to make the crust really compact.

Pop the pan into the freezer while you make the filling.

Making the FillingIn the bowl of a stand mixer add the heavy whipping cream. Using the whisk attachment, beat the cream until it has reached "stiff peaks". You'll know the cream is ready when the whisk leaves drag marks in the whipped cream as it's mixing and the cream stands straight up on the end of the beater.

Gently transfer the whipped cream to another bowl and pop it in the fridge. Do not clean the mixer bowl.

Add the cream cheese to the mixing bowl and on medium or medium high speed, beat until smooth.

Pour in the sugar and mix until smooth and well incorporated. Give the bowl a scrape with a rubber spatula.

Next, add the cooled melted chocolate and the vanilla extract to the cream cheese mixture.

Whip until fully mixed.

Remove the bowl from the stand mixer and give the mixture a final stir by hand.  

Grab the whipped cream from the fridge and scoop out 1/4 cup of the cream and add to the chocolate batter. Stir until incorporated, don’t worry about losing the air at this point, we’re trying to lighten up the chocolate mixture before we add the rest of the cream.

Next, gently spoon the remaining whipped cream on top of the chocolate mixture. Using a rubber spatula, gently fold the whipped cream into the chocolate cheesecake batter (watch the folding technique here).  This time we are trying to preserve the air whipped into the cream, so be gentle and do not rush this part.

Continue folding until there are no more streaks of cream showing.

Remove the Oreo crust from the freezer and spoon the chocolate filling onto the crust. Make sure to gently push the cheesecake batter out to the sides of the pan. Smooth the top and pop in the fridge to chill for at least 6 hours, but preferably overnight.

Unmolding The CheesecakeAfter the cake has set, run a thin sharp knife around the edge of the cake and pan to loosen.

Unbuckle the springform pan and gently lift off the ring. Transfer the cheesecake to a serving dish and slice with a sharp chef's knife. Wipe the blade clean in between each cut for clean slices.

Serve with fresh whipped cream, a drizzle of chocolate syrup, and store the leftovers in the fridge.