Nigella´s chocolate-chocoalte chip cookies

The chocolate choclate-chip cookie has always seemed to me a rampant case of gilding refined gold and painting the lily.
Provided you use enough real chocolate chips, you don´t really need the extra boost from cocoa in the dough.
But then again...there´s something very seductive in an all chocolate cookie. It´s unapologetic, which I appreciate.
Take these, from Nigella Express. She doesn´t just bump up the chocolate content with cocoa, but with chocolate as well, so that even the raw dough is irresistible. And the end result? To quote the Domestic Goddess herself, they are chocolatey to the point of madness. Yes, they are insane. But you don´t have to have all twelve at a sitting, you know. Have one (ok, two) and freeze the rest.
That way, if you suddenly decide to have a couple of friends over for coffee, you can defrost them quickly. The chips will melt every so slightly, as will your friends. And most likely, they´ll ask for the recipe, so here it is:

125 gr. dark chocolate
150 gr. flour
30 gr. cocoa
1 teaspoon baking powder
1/2 teaspoon salt
125 gr. soft butter
50 gr. brown sugar
50 gr. white sugar
1 egg, cold from the fridge
1 teaspoon vanilla extract
250 gr. dark chocolate chips ( I use Valor 70%)

Preheat oven to 170ºC.
Melt the chocolate in the microwave in a couple of minute bursts at medium strength so that it doesn´t melt too fast.
Cream the butter and sugars ( I use the Thermomix.Follow sect book rules)
Add the melted chocolate, the vanilla and the egg. At this point it´s the most delicious mousse ever.
Add the flour and the chips.
This amount makes 12 mammoth cookies of the icce-cream scoop and spoon size. They´ll take about 15-18 minutes to cook.
Watch them like a hawk, and take them out the minute the bottom´s dark.
After five minutes on the baking sheet they´ll be hard enough to transfer to a rack to cool.