@neko nomad,
I wont give you the chemical control but, if you wish to keep organic , I have very good luck with a plastic mesh that I lay overtop of the young plants . Just let the cover "float" as the plants grow, it discourages the moths from laying eggs. Using a Bt spray also is effective around here.
Ive always done crop rotation and dont allow ANY brassica in the same spot consecutively.
I grow some pretty good broccoli raab using the organic means. Ive tried cauliflower and didnt have as much luck because there would be a little worm that lived as a commensal in between the florets.
When Id pick em, Id put the entire head in a salt water mix and the worms would let loose and float on top. THIS WOULD GET ABOUT 90% and someone would still be surprised withan extra treat in theoir cauliflower. SO, we quit growing cauliflower and I dont wnat to engage in chemical warfare on my brassicas.