Cook pasta and vegetables according to their respective package directions. Drain the pasta.
Meanwhile, cut the sausage into 1-inch chunks. Heat olive oil in a pan over medium-high heat and add sausage and diced onion. Cook, stirring occasionally until sausages and onions are browned, 5 minutes.
Add the garlic and pepper flakes and cook for 1 minute, stirring frequently.
Add the tomato sauce. Bring mixture to a boil and reduce heat to low.
Toss with cooked pasta and serve with a garnish of Parmesan and a side of vegetables.