I made this in the crock pot - just dumped in all the ingredients (including the cheese! But you could probably wait and add that at the end). The cheese did separate a bit near the end but it all blended together when I stuck the immersion blender in.
I started with two fresh broccoli crowns, chopped up pretty small and raw diced onions. I added the flour at the end (mixed in with some of the soup) but I probably didn't even need it. I think the total cooking time was like 6 hours on high, but it seems like a pretty forgiving recipe.
It worked great!
Didn't freeze it, but ate it for a few days, heated up from the refrigerator.
Yay, crock pot. I am loving it. Picked it up for $3 at a garage sale.