Cook the pasta: Begin by cooking the pasta in a large pot of salted boiling water according to the package instructions. Once al dente, drain the pasta and set it aside.
Season the shrimp: While the pasta is cooking, place the shrimp in a bowl and sprinkle with Cajun seasoning. Toss to coat evenly.
Cook the sausage: In a large skillet, heat the olive oil over medium heat. Add the sliced sausage and cook until browned, about 4-5 minutes. Remove the sausage from the skillet and set it aside.
Sauté the shrimp: In the same skillet, melt the butter. Add the seasoned shrimp and cook until they turn pink and opaque, about 2-3 minutes per side. Remove the shrimp from the skillet and set it aside with the sausage.
Cook the vegetables: Add the diced onion, garlic, and bell pepper to the skillet. Sauté until the vegetables are softened and the onions are translucent, about 5 minutes.
Make the sauce: Pour in the chicken broth and heavy cream. Stir well to combine and bring the mixture to a simmer. Let it cook for about 5 minutes until the sauce begins to thicken.
Add the cheese: Stir in the grated Parmesan cheese until it melts into the sauce, creating a creamy consistency. Season with salt and pepper to taste.
Combine everything: Return the cooked sausage and shrimp to the skillet. Stir everything together and let it cook for another 2-3 minutes to allow the flavors to meld.
Toss with pasta: Add the cooked pasta to the skillet and toss until it is well coated with the sauce.
Serve: Garnish with fresh chopped parsley and serve immediately.