Mix together the flour, bicarbonate of soda, salt and cocoa powder
In a large bowl beat the butter with the sugar until soft and creamy. I used an electric whisk, but if you are feeling energetic you could use a wooden spoon. Next add the vanilla, then the eggs, one at a time, beating well between each addition.
Spoon in some of the flour and fold in. Keep doing this until all of the flour has been added, then fold in the chocolate chips.
Pop the cookie dough in the fridge for 10 minutes and line a tray with greaseproof paper.
Roll balls of dough, about the size of a golf ball and pop on your tray, leaving plenty of room between them. Press down a little and stud with chocolate chips. You will have to bake the cookies in several batches.
Bake for 8-10 minutes. You will know when they are ready as large cracks will appear. The will still be quite soft, but will crisp up as they cool and remain soft in the centre.
