Preheat oven to 400ºF. Break up the cauliflower into smallish chunks—cut off the stems and use them for another purpose (sliced thin, this makes a nice snack) or put it in your compost pile, I am not judging.
Put the cauliflower, the cut up onion and the drained chickpeas in a big bowl. Drizzle with olive oil and toss everything with your hands until the oil coats everything. Make sure everything is lightly oily. Then sprinkle on the paprika and shichimi togarashi, and toss again so everything is uniformly spiced.
Next, evenly scatter everything on your oiled baking sheets. Put in the heated oven. Position the pans on two different racks, in the center, with adequate space between for hot air to circulate. Set a timer for 12 minutes.
When the timer goes off, slide the pans out, stir everything, then put them back in the oven, reversing their locations on the racks (top pan to lower rack). Set the timer for another 12 minutes.
When the timer goes off again, you should be seeing signs that things are progressing well. You may need to stir everything and put it back in the oven for another ride, but at this point keep an eye on things so the veg doesn’t overbake. You want the cauliflower to be soft, to yield to a fork and be turning golden; the chickpeas to be crisp on the outside and soft inside; and the onion to be soft and starting to caramelize. If the onion gets scarily dark, don’t worry—pay attention to the cauliflower and the chickpeas. That onion is still going to taste great.
When everything is done, take it out of the oven. It is ready to go! Serve with a green salad if you like, or some sliced tomatoes on the side.