Pre-heat the oven to 355 ºF (180 ºC) and line a 6 x 6 inch (15 x 15 cm) square baking tin with baking/greaseproof paper.You can scale up the recipe with no problems, but you will have to increase the baking time slightly.
Mix together the crushed cookie crumbs, cocoa powder, sugar and melted butter, then press the mixture into the lined baking tin to form a firm, even layer.
Bake at 355 ºF (180 ºC) for 10 minutes, then remove from the oven and allow to cool slightly.
For chocolate cheesecake filling:
Reduce the oven temperature to 320 ºF (160 ºC).
Mix all the cream cheese filling ingredients together until smooth, then transfer the filling on top of the baked crushed cookie crust.
Bake at 320 ºF (160 ºC) for about 55 - 60 minutes, or until the filling is lightly puffed up and the middle is still slightly wobbly when you shake the baking tin.
Allow to cool at room temperature, then transfer into the fridge for at least 4 hours before pouring over the chocolate ganache.
For chocolate ganache:
In a saucepan, heat the double/heavy cream until it only just starts to boil.
Place the chopped dark chocolate into a heat-proof bowl, and pour over the hot cream. Allow to stand for 2 - 3 minutes, then stir together into a smooth ganache.
Pour the ganache over the chilled cheesecake, then return to the fridge for a further 4 hours (or overnight), until the ganache has set.
Remove from the baking tin, and slice into cheesecake bars.
The triple chocolate cheesecake bars keep well in a closed container in the fridge for 3 - 4 days.
Recipe by The Loopy Whisk (www.theloopywhisk.com).