In a large bowl, mix together broccoli, corn, and onions. Stir in sour cream, soup, and 1/4 cup shredded cheese. In a separate bowl, toss together stuffing mix and melted butter. Spread broccoli mixture into a 2 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.
