Cheesy French Onion Cauliflower

Preheat oven to 450°F. Coat a large rimmed baking sheet with cooking spray.

Heat 1 tablespoon oil in a large skillet over medium heat. Add onion and cook, stirring occasionally, for 5 minutes. Add Worcestershire, thyme and ¼ teaspoon pepper; reduce heat to medium-low and continue cooking, stirring often, until golden brown, 10 to 15 minutes more. (Add a tablespoon or two of water during cooking if the pan seems dry.) Remove from heat.

Meanwhile, arrange cauliflower slices in one layer on the prepared baking sheet. Combine the remaining 1 tablespoon oil with garlic powder and salt in a small bowl. Brush the mixture over the cauliflower slices. Roast until tender, about 10 minutes. Remove from oven and top with the reserved caramelized onions and cheese. Continue roasting until the cheese has melted, 2 to 3 minutes.