Creating the Best French Onion Broccoli Cheese Casserole is a breeze when you follow these steps:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C).
2. Prepare Broccoli: Steam or blanch the broccoli florets for about 3-4 minutes until slightly tender. Drain and set aside.
3. Mix Soup and Cheese: In a large bowl, combine the French onion soup, sour cream, garlic powder, onion powder, and half of the cheddar and mozzarella cheese. Mix until well blended.
4. Combine Ingredients: Add the steamed broccoli to the mixture and gently fold until the broccoli is evenly coated.
5. Transfer to Baking Dish: Pour the broccoli and soup mixture into a greased 9×13-inch baking dish, spreading it evenly.
6. Add Breadcrumbs: In a small bowl, mix the breadcrumbs with olive oil, salt, and pepper. Sprinkle the breadcrumb mixture evenly over the casserole.
7. Top with Cheese: Add the remaining cheddar and mozzarella cheese on top of the breadcrumbs for extra cheesiness.
8. Bake: Place the baking dish in the preheated oven and bake for 30-35 minutes or until the cheese is bubbly and golden brown.
9. Cool and Serve: Once done, remove the casserole from the oven and allow it to cool for a few minutes before serving.

Following these steps will ensure that your casserole turns out perfectly every time!