Bring a large pot of well-salted water to a boil and cook pasta according to package directions until al dente. Before draining, reserve ½ cup of the starchy pasta water.
Heat 2 tablespoons olive oil in a large sauté pan over medium-high heat until shimmering. Add zucchini and a pinch of salt, then cook without stirring for 2-3 minutes to allow browning on one side.
Stir the zucchini and continue cooking for another 2-3 minutes until tender but not mushy. The goal is slightly caramelized edges with a tender-crisp interior.
Reduce heat to medium and add garlic and red pepper flakes (if using). Cook for 30 seconds until fragrant, being careful not to burn the garlic.
Add halved cherry tomatoes to the pan and cook for 3-4 minutes, gently pressing some tomatoes with a wooden spoon to release their juices while leaving others intact for texture variation.
Add drained pasta directly to the sauté pan along with ¼ cup of the reserved pasta water. Toss everything together, allowing the pasta to absorb the flavors as the sauce thickens slightly.
Remove from heat and add the remaining tablespoon of olive oil, lemon juice, fresh basil, and Parmesan cheese. Toss to combine, adding more pasta water if needed to achieve a silky sauce.
Taste and adjust seasoning with salt and pepper. Serve immediately with additional Parmesan cheese on the side.