Place the butter, sugars and vanilla into the Thermomix bowl and chop 10 sec/speed 5. Insert Butterfly.
Whip 1 min/Butterfly/speed 4. Remove Butterfly.
Add remaining ingredients except chocolate and blend 10 sec/speed 6. Scrape down sides of bowl and repeat.
Add chocolate and fold in with a spatula. Tip dough out onto a floured piece of baking paper (I used two as I wanted two rolls) and form into a sausage shaped roll. Wrap and refrigerate for at least 30 minutes before baking.
Preheat oven to 170°C and line a cookie sheet with paper. Cut the roll into 2cm thick slices and lay on the prepared tray.
Bake exactly 12 minutes and remove and cool. The cookies will still be soft at this stage but will harden up as they cool.
Serve warm or cold..they will not last long. Thus keep the second roll in the fridge for those occasions when you need fresh cookies at 12 minutes notice!