I found this on another website, but it's worth sharing. I altered the original recipe just a little bit based on experience. As a side note, my Dad HATES broccoli, but the first time this was made for dinner, he not only ate it, but he had a second serving!!
Preheat oven to 350 degrees F. Pre-cook the broccoli about half way through. DO NOT over cook the broccoli because it will be mushy later.
In a large bowl, mix together broccoli, corn, and onions. Stir in sour cream, soup, and shredded cheese. In a separate bowl, toss together stuffing mix and melted butter. Spread broccoli mixture into a 2-3 quart casserole dish and cover with stuffing mix.
Bake in preheated oven for 30 minutes, or until heated through and browned on top. Sprinkle remaining 1 3/4 cups cheese on top and bake an additional 5 minutes, until cheese is melted and bubbly.