01 - Bring a large pot of salted water to a rolling boil. Cook pasta according to package directions until al dente. Reserve 1/2 cup pasta water before draining thoroughly.
02 - While pasta cooks, heat olive oil in a large skillet over medium heat. Add chopped onion and sauté for 2-3 minutes until softened and translucent. Add minced garlic and cook for 1 minute until fragrant.
03 - Add sliced zucchini to the skillet and sauté for 4-5 minutes, stirring occasionally, until beginning to soften and develop light golden edges.
04 - Stir in halved cherry tomatoes, salt, black pepper, and red pepper flakes. Cook for 5-7 minutes, stirring occasionally, until tomatoes start to break down and release their juices, and zucchini is fully tender.
05 - Add drained pasta to the skillet with the vegetable mixture. Pour in reserved pasta water as needed to create a light, cohesive sauce. Toss everything together thoroughly for 1-2 minutes over low heat.
06 - Remove skillet from heat. Stir in fresh basil and half the Parmesan cheese until evenly distributed. Serve immediately in bowls, topped with remaining Parmesan and extra fresh basil leaves.