In a large pot or Dutch oven, heat the olive oil over medium heat.
Add the diced onion and sauté for about 2-3 minutes until it becomes translucent.
Stir in the minced garlic and bell pepper, cooking for an additional 2 minutes until fragrant.
Add the pasta, diced tomatoes, heavy cream, vegetable broth, Cajun seasoning, smoked paprika, salt, and black pepper to the pot. Stir well to combine all ingredients.
Bring the mixture to a gentle boil, then reduce the heat to low and cover. Simmer for about 12-15 minutes, or until the pasta is al dente, stirring occasionally to prevent sticking.
If using, add the cooked chicken and frozen peas to the pot about 3 minutes before the pasta finishes cooking. Stir to heat through.
Once the pasta is cooked and creamy, remove from heat, and stir in the grated Parmesan cheese until melted and well combined.
Taste and adjust seasoning, adding more salt or pepper if needed.
Serve hot, garnished with freshly chopped parsley for a pop of color.