Bring a large pot of salted water to a boil. Cook pasta until al dente. Reserve 1 cup pasta water, then drain.
Heat a large skillet over medium-high heat. Brown the sausage 6–8 minutes, breaking it up. Drain excess grease if needed. Remove sausage to a plate.
In the same skillet, cook onions and peppers 8–10 minutes until softened and lightly browned. Add garlic and cook 30 seconds.
Add tomato paste to the pan and cook 1 minute, stirring.
Stir in crushed tomatoes, broth, vinegar, Italian seasoning, pepper flakes (optional), pepper, and a small pinch of salt. Simmer uncovered 10–12 minutes until thick.
Return sausage to the skillet. Simmer 2–3 minutes. Taste and adjust salt. Add brown sugar if needed.
Toss pasta into the sauce. Add a splash of reserved pasta water if needed to loosen.
Remove from heat. Stir in parmesan, basil (optional), and cream (optional). Serve hot.