Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Reserve 1/2 cup of pasta water, then drain the pasta and set aside.

In a large skillet, heat the olive oil over medium heat. Add the diced onion and sauté for about 3 minutes until it becomes translucent.

Stir in the minced garlic and cook for an additional minute until fragrant.

Add the zucchini, yellow squash, and red bell pepper to the skillet. Sauté for about 5-7 minutes until the vegetables are tender.

Add the cherry tomatoes, salt, and black pepper to the skillet. Cook for another 3-4 minutes until the tomatoes start to soften.

Add the cooked pasta to the skillet along with the reserved pasta water, chopped basil, Parmesan cheese, and lemon juice. Toss everything together until well combined and heated through.

Serve immediately, garnished with extra basil and Parmesan if desired.