This is a Nigella recipe and is by far the best chocolate cookie recipe I’ve ever found. It can be found here http://cook-taste-live.com/2013/05/23/nigellas-double-chocolate-chip-cookies/
I’ve made a few adjustments though – I find you can split it into about 20 portions, if you go with the 12 it recommends they’ll be enormous (not that that’s necessarily a bad thing…)! I therefore adjust the cooking time to 14 minutes, they’ll still be really gooey when you take them out of the oven so let them cool on the baking tray before moving them to a cooling rack, if you try to move them sooner they’ll fall apart and if you bake them for longer you won’t get the lovely chewy texture. The other adjustment I make is to replace the chocolate chips with white chocolate cut into chunks, I find this gives more satisfying size bits of chocolate and white chocolate is a great contrast.