Cut the broccoli into small florets (use the stems for another recipe)
Blanch the broccoli in boiling water for 1 minute, then immediately drain and shock in a bowl of ice water to stop the cooking.
Preheat the oven to 375 F.
Butter an 8x10 inch baking dish.
Warm the cream of mushroom soup in a saucepan over low heat.
Use a wooden spoon, combine the broccoli, Cheddar cheese, onion, rice, scallions, salt and pepper, soup, and half the Parmesan in a large mixing bowl.
In a small bowl, combine the melted butter and bread crumbs.
Transfer the broccoli-rice mixture to the baking dish and spread evenly.
Sprinkle the remaining Parmesan over the top and then sprinkle the bread crumbs over the cheese.
Bake, uncovered, for 20 minutes.
Increase the heat to 425 F and cook for 8 more minutes, browning the top a bit.
The sides of the casserole should be nice and bubbly.
Remove the casserole and let stand for 10 to 15 minute before serving.