Wash and trim the ends of the zucchini. Use a spiralizer to create noodles (zoodles) from the zucchini.
Heat the olive oil in a large skillet over medium heat.
Add the zucchini noodles to the skillet. Cook for 2 to 3 minutes, stirring occasionally, until they are slightly tender but still have a slight crunch. Do not overcook, or they will become watery.
Remove the skillet from the heat.
Add the pesto to the warm zucchini noodles and toss gently to coat everything evenly.
Stir in the Parmesan cheese, if using. Season with salt and pepper.
Serve immediately.
Notes
If you do not have a spiralizer, you can buy pre-made zucchini noodles at most grocery stores.
For a protein boost, add grilled chicken or shrimp during step 5.
If your pesto is very thick, add 1 to 2 teaspoons of water to help it coat the noodles better.