Cook broccoli just less than recommended on package.
While the broccoli is cooking mix the beaten egg, onion, mayo, cheese, and soup into a large casserole dish. I like to spray the dish with a little PAM for easy clean up later.
Add cooked broccoli to dish. Mix well.
Melt the butter and add it to the stuffing crumbs. Mix well and spread over top of broccoli mixture.
Bake for 30 minutes, or until topping starts to brown.