Preheat your oven to 425°F (220°C).
Take the frozen cauliflower florets out of the freezer; no need to thaw.
In a mixing bowl, combine the frozen cauliflower florets with olive oil and roast vegetable seasoning. Ensure all florets are evenly coated.
Line your baking sheet with parchment paper, if desired, and spread the seasoned cauliflower evenly on the sheet.
Place the baking sheet in the preheated oven and roast for 25-30 minutes, stirring halfway through.
Check for doneness after 25-30 minutes; cauliflower should be tender and lightly charred. For crispier results, roast for an additional 5-10 minutes.
Remove from the oven and let it cool for a few minutes before serving.