Bring a medium pot of salted water to the boil and cook the pasta according to package directions. Drain and set aside.
Meanwhile, place the shrimp into a ziploc bag and add in the cajuns seasoning and oil. Stir through the bag to completely coat the shrimp with the spices.
Heat a large rimmed pan over medium heat. Add the shrimp and cook until pink and opaque, about 2-4 minutes. Set aside.
To the same pan add 1 tbsp of oil and saute the garlic for 1 minute.
Stir in the onion, bell peppers and cook for 3-4 minutes, or until veggies soften.
Stir in the cajun seasoning plus chili powder, and cook for 1 minute more, or until fragrant. Add the crushed tomatoes, juice and lime zest. Season with salt and pepper to taste.
Simmer for about 5 minutes to allow the flavors to mild.
Stir in the cooked pasta and the shrimp, and top with grated parmesan and chopped parsley.