Step 1

Place the rack in a lower third position and preheat the oven to 325 F.

Step 2

Grease 9×9 inches square pan with baking spray and line with parchment paper leaving large overhand the side so you could easily lift the cheesecake from the pan later.

Step 3

Place whole Oreo cookies with the filing I a food processor and pulse into fine crumbs.

Step 4

Add melted butter and whisk with a fork until evenly moistened.

Step 5

Press the mixture firmly into the bottom of prepared pan and place in the fridge while making the filling.

Step 6

Melt chopped chocolate in a double broiler or the microwave (place chopped chocolate in a heat-proof bowl and melt in 20 seconds increments, stirring after each increment. Stir until smooth and silky, and then set aside.

Step 7

In a mixing bowl combine softened cream cheese, vanilla extract, sugar and sour cream. Beat until smooth.

Step 8

While running your mixer on low speed, add eggs and mix just for a few seconds to combine. Using the rubber spatula scrape down the bottom of the bowl and stir.

Step 9

Add melted chocolate and mix again on low speed. Do not mix too much after adding the eggs to avoid incorporating to muck air in the mixture or the cheesecake will rise too much, then crack and deflate too much after cooling.

Step 10

Spread the mixture over the Oreo crust. Tap the pan on the counter a few times to eliminate any air bubbles. Smooth the top and bake. If the top start browning to much tent it loosely with aluminium foil. Bake for about 45-55 minutes, or until the center is just slightly jiggly. Turn off the oven and crack the door open, leaving cheesecake in the oven for an hour. Then remove from the oven and cool to a room temperature, then place in the fridge for a few hours, or preferably overnight.

Step 11

Lift the cheesecake from the pan using paper overhang and place on a cutting board. Using a sharp knife cut in about 1×1 inch bites. If you want a clean cut, wipe the knife with paper towel after each cut. Store in an airtight container in the fridge, up to 1 week, or freeze for longer storage.

Step 12

Decorate with whipped cream and drizzle with melted chocolate if desired.