In a large mixing bowl, combine the condensed cream of mushroom soup, shredded cheddar cheese, mayonnaise, beaten eggs, diced onion, and melted butter. Mix well to combine.
Fold in the steamed broccoli florets until evenly coated with the cheese mixture.
Step 4: Assemble the Casserole
Transfer the broccoli mixture to the prepared baking dish, spreading it out evenly.
Step 5: Prepare the Topping
In a separate bowl, combine the crushed Ritz crackers, grated Parmesan cheese, and melted butter. Mix until well combined.
Sprinkle the cracker mixture evenly over the top of the broccoli mixture in the baking dish.
Step 6: Bake the Casserole
Place the casserole in the preheated oven and bake for 25-30 minutes, or until the top is golden brown and the casserole is bubbly around the edges.
Step 7: Serve and Enjoy
Remove the casserole from the oven and let it cool for a few minutes before serving.
Slice into portions and serve warm alongside your favorite main dish.
