Preheat your oven to 350°F (175°C).
Steam the broccoli florets until just tender, about 5 minutes.
In a saucepan, melt the butter over medium heat.
Stir in the flour and cook for 1 minute to form a roux.
Gradually whisk in the milk until smooth.
Add garlic powder, onion powder, salt, and pepper.
Continue cooking until the sauce thickens, about 3-5 minutes.
Remove from heat and stir in the cheddar cheese until melted.
Combine the broccoli with the cheese sauce in a baking dish.
Top with grated Parmesan and optional breadcrumbs before baking for 15 minutes.