Cook the pasta and vegetables: Bring a large pot of lightly salted water to a boil.
Cook the pasta according to package directions, adding the 3 cups (720 ml) of assorted fresh vegetables during the final 2 minutes of cooking time.
Drain well, then return the pasta and vegetable mixture to the hot pot.
Add the halved cherry tomatoes, cover the pot, and set aside to keep warm.
Create the creamy sauce: In a medium saucepan, whisk together the vegetable broth, flour, and salt until no lumps remain.
Stir in the milk and dry sherry.
Bring the mixture to a boil over medium heat, stirring constantly, until it thickens and bubbles.
Continue to cook and stir for 2 more minutes.
Remove the pan from the heat.
Finish and serve: Stir the finely shredded Parmesan cheese, chopped basil, and snipped thyme into the sauce until the cheese is melted and smooth.
Pour the sauce over the warm pasta and vegetables.
Toss gently to coat everything evenly.
Serve immediately, sprinkled with sliced green onions if desired.