In a large pot or deep skillet, combine spaghetti, zucchini, squash, cherry tomatoes, bell pepper, carrots, red onion, and garlic.
Pour in the vegetable broth and drizzle with olive oil. Season with salt and pepper.
Bring the mixture to a boil over high heat, then reduce to medium. Cook uncovered for about 10–12 minutes, stirring occasionally, until the pasta is al dente and most of the liquid has evaporated.
Stir in Parmesan cheese and heavy cream if using. Mix until the cheese is melted and the sauce is creamy.
Taste and adjust salt and pepper as needed.
Serve immediately, garnished with fresh basil or parsley. Eat with joy—and maybe a second helping.