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. Don't thaw them first. Liberally spray them with olive oil, then sprinkle them with kosher salt, black pepper, garlic powder, and dried thyme.
2 pounds frozen broccoli florets, Olive oil spray, ½ teaspoon Diamond Crystal kosher salt, ¼ teaspoon black pepper, ½ teaspoon garlic powder, ½ teaspoon dried thyme
Bake the florets until browned and crispy, about 30 minutes. Start checking after 20 minutes and be prepared to bake for as long as 40 minutes - it all depends on the size of the florets and on how hot your oven runs. Serve immediately.
Video
Notes
Seasonings, especially salt, are just guidelines. Adjust to taste.
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.
To prevent sogginess, make sure the florets are in a single layer and aren't crowded. If needed, use two baking sheets and rotate them midway.
I don't recommend keeping leftovers. Even though the freshly baked broccoli comes out of the oven crispy, it turns mushy in the fridge. If you must store leftovers, keep them in an airtight container in the fridge for up to three days. Line the container with paper towels to absorb excess moisture and replace them daily. Reheat the leftovers uncovered in a 350°F oven. I don't recommend freezing the leftovers.