01 - Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Reserve 1/2 cup pasta water before draining.
02 - Heat olive oil in a large skillet over medium heat. Add red onion and sauté for 2-3 minutes until softened and translucent.
03 - Add minced garlic to the skillet and cook for 30 seconds until fragrant, being careful not to burn it.
04 - Stir in zucchini slices and cook for 4-5 minutes, stirring occasionally, until just tender but still slightly crisp.
05 - Add cherry tomatoes, Italian herbs, red pepper flakes, salt, and pepper. Cook for 4-5 minutes, stirring occasionally, until tomatoes soften and release their juices.
06 - Toss in baby spinach and cook for 1-2 minutes until just wilted.
07 - Add drained pasta to the skillet. Toss everything together thoroughly, adding reserved pasta water as needed to create a silky coating sauce.
08 - Remove from heat. Stir in fresh basil leaves and sprinkle with grated Parmesan cheese if desired. Serve immediately with extra basil and a drizzle of olive oil.