Cook the pasta according to the package directions, in salted water. Once the noodles are al dente, drain them, reserving ½ cup of the pasta cooking water. Set the noodles aside to keep warm.

While the pasta cooks, combine the olive oil and 2 tablespoons of the Cajun seasoning. Coat the shrimp with this mixture.

Melt 2 tablespoons of butter in a large skillet over medium heat. Add the shrimp in a single layer across the bottom of the skillet. Cook for 2 minutes on each side, until the shrimp are opaque, firm, and curl slightly. Only turn the shrimp over once while cooking. Do not overcook the shrimp or it will turn rubbery and chewy. Remove the shrimp from the pan, and set aside on a clean plate.

In the same pan over medium-high heat, melt the remaining tablespoon of butter. Add the onion, garlic, tomato, and the remaining 1 teaspoon of Cajun seasoning. Saute until the onions are translucent, about 4 - 5 minutes.

Lower the heat to medium, and add the heavy cream. Stir to combine. Allow the sauce to come to a low simmer and cook for 2 minutes.

Turn off the heat. Add the cheese and stir until well-combined, smooth, and creamy. Add the cooked pasta to the pan, and toss to coat.

If the sauce seems too thick, add one spoonful of the reserved pasta water at a time, stirring, until the sauce is thin enough. 

Add the shrimp to the pan, and toss to combine one more time.

Serve immediately with a sprinkle of fresh chopped parsley, and a little extra grated parmesan cheese on top.