Preheat your oven to 425 degrees F (218 degrees C). Coat a 9×13-inch baking dish with some nonstick cooking spray, then set aside. Arrange a steamer basket in a saucepan with about 1 inch of water in it. Put the broccoli florets in the steamer basket, cover with a lid, bring water to a boil over high heat, then steam the broccoli for about 3-5 minutes until just tender, then set aside to cool slightly.