Cook the linguine in a large pot of salted boiling water according to package instructions until al dente. Drain and set aside.
In a large bowl, toss the shrimp with Cajun seasoning to coat evenly.
Heat olive oil in a large skillet over medium heat. Add the shrimp and cook for about 2-3 minutes per side until they turn pink and are cooked through. Remove the shrimp from the skillet and set aside.
In the same skillet, add diced onion and bell pepper. Sauté for about 4-5 minutes until softened.
Add minced garlic and cook for an additional 1 minute until fragrant, stirring frequently.
Pour in the diced tomatoes and let it simmer for 3-4 minutes.
Lower the heat, then stir in the heavy cream and let it come to a gentle simmer. Cook for about 2 minutes until slightly thickened.
Stir in the grated Parmesan cheese until melted and well mixed into the sauce. Season with additional salt and pepper if desired.
Add the cooked pasta and shrimp to the skillet, tossing until everything is well coated with the creamy Cajun sauce.
Remove from heat and garnish with fresh parsley before serving.