Cook the noodles according to the package directions, drain them, and toss them with 1 Tbsp. oil to prevent sticking.
Meanwhile, using a food processor (this one is worth pulling it out for) or a box grater, shred the zucchini, yellow squash, and carrots to yield 7 – 9 cups of vegetables.
Heat a large heavy skillet over medium heat, add the remaining 3 Tbsp. of oil, and when it is hot, add the garlic. Stir the garlic for about 30 seconds until it is fragrant but don’t let it brown, then add the shredded vegetables including any of their liquid, the sausage (optional), and the salt.
Cook the vegetables (and sausage) for about 10 minutes or until the pasta is done, stirring occasionally.
Top the noodles with the vegetables (and sausage) and serve it with plenty of cheese and lots of freshly ground black pepper at the table or refrigerate it for up to 3 days.