Creating Broccoli Cheese Casserole is straightforward when you follow these steps:

1. Preheat Oven: Preheat your oven to 350°F (175°C).
2. Prepare Broccoli: Steam the broccoli florets until they are tender but still crisp, about 3-5 minutes. Drain and set aside.
3. Mix Ingredients: In a large mixing bowl, combine the cream of mushroom soup, sour cream, mayonnaise, garlic powder, salt, and black pepper. Mix well.
4. Add Onion and Cheese: Stir in the chopped onion and 1 cup of shredded cheddar cheese into the mixture.
5. Combine with Broccoli: Fold the steamed broccoli into the soup mixture until well coated.
6. Prepare Casserole Dish: Grease a 9×13-inch casserole dish with cooking spray or butter.
7. Transfer Mixture: Pour the broccoli mixture into the prepared casserole dish and spread evenly.
8. Add Topping: In a small bowl, combine the crushed crackers with melted butter. Sprinkle this mixture evenly over the top of the broccoli mixture.
9. Bake: Place the casserole in the preheated oven and bake for 30-35 minutes, or until bubbly and golden.
10. Serve: Remove from the oven and allow it to cool slightly before serving.

These steps will guide you in creating a delicious Broccoli Cheese Casserole that is sure to impress your family and friends.