This easy Cheesy Broccoli Casserole comes together in just a few simple steps. We'll blanch the broccoli first to ensure it's perfectly tender, then create a velvety cheese sauce before baking everything to golden perfection.

1. Step 1: Preheating ensures even cooking throughout the casserole.

   Preheat your oven to 375°F (190°C) and lightly grease a 2-quart baking dish.

2. Step 2: Don't overcook the broccoli as it will continue to cook in the oven.

   Bring a large pot of salted water to a boil. Add the broccoli florets and blanch for 3-4 minutes until bright green and just tender. Drain well and set aside.

3. Step 3: Cooking the flour removes the raw taste and creates the base for your cheese sauce.

   In a medium saucepan over medium heat, melt 2 tablespoons of butter. Add the flour and whisk continuously for 1-2 minutes to create a roux.

4. Step 4: Add milk slowly while whisking for a smooth sauce without lumps.

   Gradually whisk in the milk, stirring constantly to prevent lumps. Continue cooking for 3-4 minutes until the mixture thickens slightly.

5. Step 5: Low heat prevents the cheese from separating and becoming grainy.

   Reduce heat to low and add 1 1/2 cups of shredded cheddar cheese and the cream cheese. Stir until completely melted and smooth.

6. Step 6: Mustard powder enhances the cheese flavor without adding a mustard taste.

   Stir in the garlic powder, onion powder, mustard powder, salt, and pepper. Taste and adjust seasonings if needed.

7. Step 7: Ensure all broccoli pieces are coated with sauce for maximum flavor.

   Place the drained broccoli in the prepared baking dish and pour the cheese sauce evenly over the top. Gently stir to coat the broccoli with the sauce.

8. Step 8: Buttering the breadcrumbs helps them become golden and crispy.

   In a small bowl, combine the remaining 1 tablespoon of melted butter with the panko breadcrumbs. Sprinkle the remaining 1/2 cup of shredded cheddar over the casserole, then top with the buttered breadcrumbs.

9. Step 9: Look for a golden-brown top and bubbling edges as signs that your casserole is done.

   Bake uncovered for 25-30 minutes until the top is golden brown and the edges are bubbly.

10. Step 10: Resting allows the casserole to set and makes it easier to serve.

    Let the casserole rest for 5 minutes before serving to allow the sauce to set slightly.

This casserole can be assembled up to 24 hours in advance and refrigerated before baking. Just add 5-10 minutes to the baking time if cooking from cold. Leftovers can be stored in the refrigerator for up to 3 days and reheated in a 350°F oven until warmed through.