Pop the Corn:Heat olive oil in a large pot over medium heat. Add popcorn kernels, cover with a lid, and shake occasionally until popping slows down.
Prepare Topping:In a small bowl, mix Parmesan, lemon zest, garlic powder, salt, and pepper.
Combine:Pour popped popcorn into a large bowl. Drizzle with melted butter (if using) or olive oil, and sprinkle the Parmesan mixture evenly, tossing well to coat.