Ladies! Are those flowers at the top? Any plants with flowers have 'bolted' which is usually the result of them drying out at the roots at some point. If you cut the flowers off, the sprouts themselves may continue to grow but it's possible that the developing sprouts will now 'blow' on the affected plants.
it looks more like one of the jersey walking stick cabbages. I'd pinch out the top to force it to make the brussels.