Preheat the oven to 180°C/350F and line a baking tin with greaseproof paper.
Place the crushed oreos, cocoa powder and flour into a bowl and stir to combine. Rub the butter into the mixture until no lumps remain. Place the bowl into the microwave and heat on high for 10 seconds to soften the butter.
Press into the baking tin and bake for 10 minutes.
Meanwhile, mix the peanut butter and cream cheese in a bowl to smooth out the mixture and combine. Add in the egg and sugar and combine to form a smooth mixture.
Pour into the tin and spread evenly.
Place the tin in a larger tray and pour hot water half way up the sides of the tin. Place in the oven and bake for 45 minutes or until golden on top.
Allow to cool fully.
Place the chocolate into a heatproof dish and melt in the microwave for approximately 40 seconds on high, stir the coconut oil in until smooth.
Allow to cool slightly then pour over and spread evenly over the top. Refrigerate or allow 3 hours for the chocolate to harden.