• Preheat oven 180C | 356F. Grease a shallow small – medium sized round springform cake pan.
  
  

For the Base:

• Add the Oreos into a food processor and process until crumbs form. Add the other 'base' ingredients, and process again until combined well. Press the mixture down into the prepared tin. Refrigerate and prepare cheesecake.
  
  

For the Cheesecake:

• Combine the cream cheese, sour cream (or yogurt), eggs and sweetener/sugar in a bowl. Beat on low speed with an electric hand beater/mixer until smooth and combined.
• Add the cornflour/starch, orange rind and vanilla, beating for a further 2 minutes on low speed until smooth and creamy.
• Pour onto chocolate base into the prepared pan and spoon the warmed Nutella over the top. Swirl chocolate around with the back of a knife to create a marble effect.
• Bake in the oven for 30 – 40 minutes, or until just set in centre.
• Meanwhile, prepare your berries, like in this recipe here (just leave out the peanut butter, or include it)!
• When cheesecake is set and top has slightly browned, remove from oven and allow 15 minutes to cool. Place in the fridge for 1 hour to chill.
  
  

For the Hot Fudge Sauce:

• Stir together the milk and Nutella in a microwave safe dish. Heat for 30 seconds, remove and mix again until runnier in consistency (like a Hot Fudge Sauce). Alternatively, place in a heatproof dish over a pot of boiling water and whisk until smooth and heated through (be careful not to get any water in the Nutella, or it will seize).
• Once cheesecake has chilled, top with chocolate covered berries, drizzle with the Nutella Hot Fudge Sauce and optional (not really) whipped cream.