In a medium bowl, add the unthawed frozen broccoli, drizzle with the olive oil and season with salt and pepper. Toss to coat the broccoli in oil.
Transfer the broccoli to a sheet pan, spread the broccoli evenly across the pan so there is space between each piece of broccoli.
Roast for 15-20 minutes, or until broccoli is tender and getting brown and caramelized in spots.
Remove from oven, immediatly zest the lemon over the broccoli, then grate the parmesan cheese over the broccoli if using. Slice the lemon into wedges and squeeze some lemon juice over the broccoli. Serve with additional lemon wedges if desired.
Notes
Broccoli does not need to be thawed before cooking. Store leftovers in the fridge for 1-2 days.If you want to save yourself an extra dish to wash, you can skip the bowl and toss the broccoli in the oil directly on the sheet pan. However, it is a harder to get the frozen broccoli fully coated in the oil because the temperature makes the oil thicker and less viscous. I find it works much better if you do this in a bowl before transferring the broccoli to the sheet pan.