Bring a large pot of salted water to a boil. Cook the pasta according to package instructions until al dente. Before draining, scoop out and set aside 1–2 cups of the cooking water, then drain the pasta.

Warm the olive oil in a large, deep skillet over medium heat. Add the shrimp and cook about 3–4 minutes, turning once, until they turn opaque. Remove the shrimp from the pan and keep aside.

Using the same skillet, add the sliced smoked sausage and cook 2–3 minutes until the edges are lightly crisp. Transfer the sausage to a plate with a slotted spoon and set aside.

Add the diced shallot and sliced red bell pepper to the pan and sauté for 1–2 minutes, stirring occasionally, until they begin to soften.

Stir in the chopped garlic and cook another minute, until fragrant but not browned.

Mix in the Cajun seasoning and tomato paste, stirring for about 30–60 seconds to toast the spices and meld flavors.

Pour in the chicken stock and scrape the bottom of the pan to loosen any browned bits, allowing the liquid to deglaze the skillet.

Add the half-and-half, stir to combine, then reduce the heat and simmer gently for 2–3 minutes until the sauce slightly thickens.

Return the cooked shrimp and smoked sausage to the pan and heat through, folding them into the sauce so everything is evenly coated.

Add the drained pasta to the skillet and toss to coat in the sauce. If the sauce seems too thick, loosen it with a splash of the reserved pasta water until you reach the desired consistency.

Stir in the grated Parmesan and chopped parsley, taste and adjust seasoning with salt and pepper, then serve immediately.