Florets must be dry, if they are wet from rinsing pat try with paper towels. Place in glass 9x13 pan and pour olive oil over broccoli. Season with salt and pepper toss to evenly distribute.
Roast in 400° oven for 15 minutes.
Remove from oven and grate zest over broccoli. Give a quick stir to distribute the zest and flip the broccoli so it browns evenly.
Return to oven for approximately 15 minutes, until florets are pierced easily with knife. Serve immediately.