Bring a large pot of salted water to a boil and cook the refrigerated cheese tortellini according to package directions; drain and set aside.
Heat 1 tablespoon of the olive oil in a large nonstick skillet over medium-high heat. Add the shrimp, sprinkle with Cajun or Creole seasoning, and cook just until they turn pink, about 1–2 minutes per side; remove shrimp to a plate (they will finish cooking later).
Add the remaining 1 tablespoon olive oil to the skillet. Add the diced onion, diced red bell pepper, and sliced smoked sausage and cook, stirring occasionally, until the sausage is browned and the vegetables are softened, about 5–7 minutes.
Add the minced garlic to the skillet and cook 1 minute, until fragrant.
Reduce heat to medium and stir in the butter, heavy cream, dried thyme, and cayenne pepper if using. Simmer gently for about 5 minutes until the sauce thickens slightly.
Stir the freshly grated Parmesan into the cream sauce until melted, then return the cooked shrimp to the skillet and taste; season with salt and pepper as needed.
Add the drained tortellini to the skillet and toss gently to coat with the sauce and warm through. Sprinkle with chopped parsley and serve.