If you're not able to find pre-chopped cauliflower florets, it's fairly easy to chop up a head of cauliflower yourself! Remove any leaves and discard or set aside (these can be roasted), then wash the cauliflower and pat it dry. Cut the stem so it can stand on your counter, then chop the head in half. Use your knife to core the cauliflower and remove the rest of the main stem. At this point, most of the florets should naturally separate, but you can easily cut them apart if need be.