See :https://en.wikipedia.org/wiki/Rapini
I recall last year there were posts regarding the rapini broccoli, I think it was the concensus that you treat it as if spinach, Plant direct, thin lightly and crop early. The flowering heads are similar to spinach , ie plants will be 250mm high, and the "sprouts" are produced in 8-12 weeks from sowing. Expect to harvest twice and then replace.
Most advise scalding the harvested shoots prior to steaming, to reduce the "broccoli bitterness", and retain best nutrients. Now that its "permitted"(!), a little salted butter on serving is my preference.
