Bring a large pot of water to boil. Add 2 tablespoons of salt and the pasta. Cook according to package directions until al dente, about 10-12 minutes. Reserve 1/2 cup pasta water before draining.

While pasta cooks, heat olive oil in a large skillet over medium-high heat. Add sliced andouille sausage and cook for 4-5 minutes until browned on both sides. Remove sausage and set aside.

In the same skillet with the sausage drippings, add diced onion and bell peppers. Cook for 5-6 minutes until vegetables are softened and slightly caramelized.

Add minced garlic, Cajun seasoning, smoked paprika, and cayenne pepper. Cook for 1 minute until fragrant, stirring constantly to prevent burning.

Pour in chicken broth to deglaze the pan, scraping up any browned bits. Let it simmer for 2 minutes to reduce slightly.

Reduce heat to medium-low and slowly pour in heavy cream, stirring constantly. Simmer for 3-4 minutes until sauce begins to thicken.

Return the cooked sausage to the skillet and stir in the drained pasta. Add grated Parmesan cheese and toss everything together until well coated.

If the sauce seems too thick, add reserved pasta water 1-2 tablespoons at a time until desired consistency is reached. Season with salt and black pepper to taste.

Serve immediately, garnished with chopped green onions and additional Parmesan cheese if desired.