A Duh moment!
When we eat broccoli, we don't always eat the stems. I chop them up and feed them to "the lads" (my voracious indoor composters).
We love broccoli and cheese soup and it just dawned and me that I should freeze the stalks and make soup when I have enough accumulated. I'll also put in the florets too of course.
Is there any reason that this wouldn't work?