Simply mix 200g of unsalted butter with 300g of caster sugar - I like to use golden sugar when i'm baking. When fully combined, whack in one egg, then your 75g of cocoa powder and 275g of plain flour. Things get a bit dry at this point so add a couple of tablespoons of milk and it should all combine into a nice thick chocolatey dough. Then you can add your chocolate, the more the merrier. The recipe stipulates 3 large bars, I used 2 big bars of white chocolate (milky bar) and 1 bar of milk (galaxy) - but you could do 1 dark, 1 milk, 1 white or any other combo you prefer!
Line some baking trays with baking paper and separate the mixture into 12 handful sized balls, spread them out (I did four per baking tray, you don't want a large tray bake cookie - or maybe you do!)
You'll be left with soft gooey chocolatey deliciousness and you can gobble them all up in one go and then feel sick and sit around for the rest of the day doing nothing. Not that that's what I did.. Honest.
All washed down with a cup of tea, lovely.
Bake them for 10-12 minutes at 200 degrees (Gas Mark 6) and then leave them to cool on the baking tray for 30 minutes - yes it's torture but so worth it!