Konasdad, pick away, yes they do grow like the collards, same family, brassica. Anyways, if you want the sprouts to get even bigger (hoping that they don't open up somewhat and are not those nice little round cabbages anymore), remove the bottom leaves as you harvest. Removing the leaf under the sprout will allow that sprout to get even bigger.
What I have done in the past too, if I want a plant to harvest for a large family dinner is to pinch out the very top of the plant, once it has matured. This prevents upward growth, puts the power to producing the fruit and forces the plant to mature the fruit fast. It is a good way to get a bountiful harvest all at once. Oh those brussels sprouts. Yes, the hard frost alters the chemical the plant produces and the the sprout does sweeten. Beautiful and most wonderful day, loving our lives. Cindi