In a bowl, mix shrimp with cajun seasoning then set aside until ready to use.
½ pound medium raw frozen shrimp, 1 teaspoon Cajun seasoning
In a large pot, bring 8 cups of water to a rolling boil and add salt. Add the pasta and cook for 8-10 minutes or until al dente. Reserve ½ cup of pasta water and discard the rest.
8 ounces spaghetti or fettuccine, 8 cups water, 1 tablespoon salt
In a large skillet, heat1 tablespoon of oil over medium heat. Add the shrimp in a single layer and cook each side for 2 minutes or until cooked. Remove from oil and transfer to a bowl.
¼ cup olive oil
Add the rest of the oil and butter to the skillet. Add the garlic and cook until limp and aromatic.
½ stick butter, 6 cloves garlic
Next, add the cajun seasoning and ¼ cup of reserved pasta water. Stir and cook for a minute. Squeeze half of the lemon into the sauce. Cut the remaining half into quarters for serving later.
1 pc lemon, 2 tablespoons Cajun seasoning
Add the cooked pasta and toss to coat with sauce. Turn off the heat and transfer pasta to serving dish or to individual plates.
Top with cooked shrimp and sprinkle with some chopped parsley and grated parmesan, if desired.
1 tablespoon parsley, 2 tablespoons grated parmesan