Fill a large pot with water and bring to a rolling boil. Add salt and cook the spaghetti for about 8-10 minutes until al dente.

In a large skillet, heat olive oil over medium heat and sauté minced garlic for about 1 minute until fragrant.

Add sliced zucchini to the skillet and sauté for 5-7 minutes until tender but still slightly firm.

Stir in lemon zest and juice, and season with salt and pepper. The sauce should take on a golden hue.

Add the drained spaghetti to the skillet and toss with the zucchini and garlic, adding reserved pasta water as needed.

Turn off the heat and stir in Parmesan cheese and parsley until well combined.

Serve the pasta in warm bowls, garnishing with extra Parmesan and red pepper flakes if desired.