Bring a large pot of salted water to a rolling boil. Add penne pasta and cook 8-10 minutes until al dente. Reserve 1/2 cup of pasta water before draining.

Heat olive oil in a large skillet over medium-high heat for 1-2 minutes until shimmering.

Add chopped red onion and carrot, stirring frequently for about 2 minutes until fragrant and softening.

Add broccoli florets and bell pepper, sautéing for another 2 minutes until they change color and are tender but still crisp.

Introduce diced zucchini and yellow squash, stirring for an additional 3 minutes until tender and vibrant.

Stir in minced garlic, diced tomatoes, and Italian seasoning. Cook for 2 minutes until fragrant.

Add drained pasta to the skillet with vegetables, drizzle with reserved pasta water and lemon juice, tossing to combine.

Sprinkle in Parmesan cheese and parsley, tossing to incorporate. Serve immediately, garnished with extra parsley and lemon wedge if desired.