Place the saucepan over medium-high heat. Add the oil and heat.
Place a few kernels of corn in the pot and when they start popping add the rest of the popcorn.
Cover the pan with the lid and gently shake the pan over the burner while the corn is popping. If you can keep the lid slightly off the pan the steam can escape and the popcorn will be crispier.
Listen for the corn to stop popping then remove from the heat and immediately pour into a large serving bowl.
Pour the olive oil over the popped corn then sprinkle with the rosemary, cheese, and salt to taste. Stir and enjoy.