Melt the butter in the microwave and set aside. Open each Oreo cookie and separate the biscuits from the filling. Set the filling aside and add the cookies to a food processor fitted with the rotating blades. Crush the biscuits until fine and, as the blades are still rotating, pour in the melted butter. Line the bottom of a springform pan with baking paper and the sides with a cake collar (optional). Spread biscuit mixture evenly all over the bottom of the pan. Chill in the fridge for the time being.
Soak half of the gelatin sheets (10 g) in cold water for 5 minutes. Gently heat the raspberry jam in the microwave, stirring from time to time, until steaming hot. The jam will loosen in texture. Squeeze excess water from the softened gelatin sheets and stir into hot jam. Set aside to cool.
Melt ¾ of the chocolate (150g) in the microwave at the lowest setting, checking every minute. Combine the cream cheese, powdered sugar and Oreo fillings in a bowl and mix at medium speed for 2-3 minutes, until combined and smooth. Add the melted chocolate (ideally it should not be hot but barely warm, so let it cool some before adding it). Start the mixer again and whisk it all in until smooth.
Soak the rest of the gelatin sheets (10 g) in cold water. Heat 100 ml of cream and stir in the soaked gelatin to melt, adding it little by little. If you notice that the gelatin does not melt immediately when about halfway, microwave the cream some more. Adding the gelatin might have cooled the cream too much to effectively melt all of the gelatin. Slowly pour the gelatin and cream mixture into the other bowl, mixing at low speed until even and combined.
Take the crust out of the fridge and pour in the chocolate cheesecake filling. To achieve a flat top, gently shake the springform pan and tap the pan on the countertop a couple of times. This might even cause some air bubbles to come to the top. Place in the fridge for cooling about 10 minutes.
Take the cheesecake out of the fridge, it will still be very wobbly, but hopefully slightly firmer. Using a spoon, pour the jam and gelatin mixture all over the surface of the cake. Return the cake to the fridge and let it set for a minimum of 2 hours (or better overnight).
When the cake is set, make the ganache. Warm up remaining cream (150 ml) and take away from the heat just before it reaches boiling temperature. Add remaining chocolate (80 g) to the cream and stir until combined. Let sit until it reaches room temperature, you can speed up the process by placing the bowl in an ice bath and stirring from time to time. When cooled to room temperature, pour the ganache over the cheesecake starting from the middle and moving in circles outwards, letting it gently drop down the sides. Decorate with freeze-dried raspberries. Let the ganache set in the fridge before cutting.
Notes
The nutritional information provided is made with an online calculator and only meant to be used as a guideline.