Bring a large pot of salted water to a boil. Cook pasta according to package directions until al dente. Drain and set aside, reserving ½ cup of pasta water.

In a large skillet, heat olive oil over medium heat. Add sliced sausage and cook until browned and slightly crisp, about 4–5 minutes. Remove from skillet and set aside.

Add onions, bell peppers, and garlic to the skillet. Sauté 3–4 minutes until softened. Add cherry tomatoes if using and cook 2 more minutes.

Reduce heat to medium-low. Stir in butter, smoked paprika, Cajun seasoning, and red pepper flakes. Slowly pour in chicken broth and heavy cream, stirring to combine. Simmer 2–3 minutes until slightly thickened.

Add cooked pasta and sausage back to skillet. Toss to coat in sauce. Add reserved pasta water if needed to loosen sauce.

Stir in Parmesan cheese until melted. Taste and adjust seasoning with salt, black pepper, or extra Cajun seasoning.

Plate pasta in bowls. Garnish with chopped parsley and green onions. Serve immediately.