Set the butter in a medium sized frying pan or skillet. Once it begins to melt, grate the fresh ginger over it.
Keep cooking the butter as it melts, then sputters then foams. The milk solids will separate, and appear as cream colored bits then they will start to brown. Once the butter starts to go quiet, smells nutty and most or all of the bits are browned, transfer to a heatproof bowl. Add the ground ginger and stir it in, then leave to cool for 5-10 minutes.
Note: if the butter has black bits it’s burnt! You’ll have to start over.
Add the sugars, cinnamon, salt and vanilla to the butter in the bowl and whisk very well: the mix will start out loose and the sugar separate but as you mix it will start to become cohesive and get a bit of shine (see the video).
Pour in the molasses and mix well.
Add the egg and yolks and whisk for a good 30-45 seconds, until well mixed.
Add the flour, baking powder and baking soda and stir until no flour bits remain. Set the dough covered with cling wrap, in the fridge to chill for 3-4 hours.
Preheat the oven to 350 F and line two cookie sheets with parchment paper (grease, or rubbing the back of the butter wrapper onto the pan before you put the parchment will help keep it in place).
Portion the cookies onto the prepared pans (1.5-2.5 tablespoons of dough per cookie). Roll the dough balls in some granulated sugar. Space the dough out, leaving at least a one inch diameter around the cookies as they will spread.
Bake for 10-12 minutes (less for a 1.5 tablespoon dough, more for a 2-2.5 TB dough) until the edges are just golden and the cookies have puffed up and cracked.
Let cool on the pan briefly, transfer to a cooling rack.