Preheat the oven to 425°F. Line a large, rimmed baking sheet with high-heat-resistant parchment paper.
Arrange the frozen broccoli florets in a single layer on the prepared baking sheet.
Liberally spray the florets with olive oil, then sprinkle them with kosher salt, black pepper, garlic powder, and dried thyme.
Bake the florets until they are browned and crispy, for about 30 minutes. Serve immediately.
Video
Notes
Some bags of frozen broccoli contain, in addition to proper florets, lots of really tiny crumbs. These will burn in the oven, so it's best to throw them out and just roast the florets - larger and smaller ones can be baked together.
This is one of those rare recipes where I don't recommend keeping leftovers. Even though the freshly baked broccoli emerges from the oven nice and crispy, it turns mushy and soggy after spending a night in the fridge. So, try to only make as much as you can eat right away.
If you must store leftovers, keep them in an airtight container in the fridge for up to three days and reheat them uncovered in a 350°F oven. I don't recommend freezing the leftovers.