Cut the top off a good-sized marrow and scoop out the seeds. Pack the cavity with dark brown sugar: a 3lb/1.5kg marrow will hold as much as 2lb/1kg sugar. Make a small hole in the bottom of the marrow with a knitting needle, put the marrow in a nylon stocking and hang it over a bowl. (Mine is suspended from the rungs of an upturned stool, with the bowl sitting on the underside of the seat, and covered loosely with a black bin bag.) Allow the fermenting liquid to drip into the bowl: depending on the size of the marrow, the process will take around two months. Decant the syrupy brown liqueur into bottles. You can drink it straight away or keep it to mature.