Preheat oven to 350 degrees. Butter a 9×13 baking dish.
In a medium bowl, whisk together mushroom soup, mayonnaise, eggs, & onion.
Place broccoli in a very large mixing bowl. Stir in the soup mixture & thoroughly combine. Stir in the shredded cheese.
Spread mixture into your casserole dish, and sprinkle with salt, pepper, & paprika. Bake 45-60 minutes in a preheated oven, until the top has started to brown.