Start by boiling a large pot of salted water for the pasta.
Add the pasta and cook according to package instructions until al dente.
While the pasta cooks, heat olive oil in a large skillet over medium heat.
Add chopped onion and sauté until translucent.
Stir in minced garlic and cook for an additional minute.
Remove the sausage from its casing and add it to the skillet.
Cook the sausage until browned, breaking it apart with a spoon.
Add canned tomatoes, oregano, salt, and pepper; let simmer for 10 minutes.
Drain the pasta and add it to the skillet, tossing to combine.
Serve hot, garnished with fresh basil and grated Parmesan cheese, if desired.