In a bowl combine cocoa powder, sugar and self raising flour and stir to blend.
In a separate bowl beat together egg and melted butter until well combined. Add the dry ingredients and stir until the mixture becomes smooth.
Transfer the batter into a greased pan (6 x 6 inches/ 15 x 15 cm or even smaller as this is half the yield of a normal brownie), lined with parchment paper. Bake for about 20 minutes or until a toothpick inserted in the centre comes out clean.
Let cool until room temperature and then cut into bite sized pieces.
Using an electric mixer beat together cream cheese, vanilla, ground pistachio and powdered sugar until creamy.
In a large mixing bowl whip the cream until very thick.
Melt the chocolate in a heatproof bowl over a pan of gently simmering water (double boiler).
With a rubber spatula gently fold the melted chocolate into the cream cheese mixture. Fold in also the whipped cream, mixing very carefully until uniform.
Arrange half of the brownie bites on the bottom of 4 to 6 glasses (depending on their size). Spoon the pistachio mixture over the brownies. Arrange the rest of the brownie bites on top.
Alternatively you can make 2 layers of cheesecake and 2 layers of brownie bites in each glass.
Cover with cling film and let sit in the fridge for at least 4 hours before serving.
Make sure the heavy cream has been refrigerated at least 6-8 hours before whipping it.This cheesecake keeps 2-3 days in the fridge.