Boil the pasta. Bring a large pot of salted water to a boil. Cook the pasta until just shy of al dente (1–2 minutes less than package). Reserve 1 cup of pasta water, then drain.

Brown the sausage. In a large skillet over medium-high heat, add 1 tablespoon olive oil. Crumble in the sausage and cook, breaking it up, until browned and cooked through, 6–8 minutes. Transfer to a plate, leaving drippings in the pan.

Sauté onions and peppers. Add remaining 1 tablespoon olive oil to the same skillet. Stir in sliced onion and peppers with a pinch of salt. Cook, stirring often, until softened and lightly caramelized, 8–10 minutes.

Add garlic and tomato paste. Stir in the garlic and cook 30 seconds until fragrant. Add tomato paste and cook 1 minute, stirring, to toast it. This step deepens the flavor and removes raw acidity.

Deglaze with wine. Pour in the white wine. Scrape up any browned bits from the bottom with a wooden spoon. Simmer 2–3 minutes until reduced by about half. If not using wine, use chicken broth.

Build the sauce. Return sausage to the pan. Add crushed tomatoes, oregano, and red pepper flakes if using. Bring to a gentle simmer and cook 5–7 minutes, stirring occasionally. Taste and season with salt and pepper.

Toss with pasta. Add the drained pasta to the skillet. Pour in a splash of reserved pasta water and toss over medium heat until the sauce loosens and coats the noodles. Add more pasta water as needed to achieve a silky consistency.

Finish and serve. Turn off heat. Stir in butter and Parmesan until melted and glossy. Top with fresh basil or parsley. Serve immediately with extra Parmesan.