Dry the chicken breasts with paper towels and place them in a large bowl. Pour two tablespoons of olive oil over them. Then, using tongs, stir the breasts around to coat them completely with the oil.
Next, add three tablespoons of the Cajun seasoning blend. Then, using the tongs, stir the breasts around to coat them completely in the Cajun seasonings.
Heat a large deep skillet or Dutch oven, with a lid, to medium-high heat and add two tablespoons of olive oil.
Then, add the seasoned chicken breasts to the hot oil, cover them, and cook for 3-4 minutes (or until they have a dark blackened coloring on the underside). Make sure to keep an eye on the chicken, it can go from blackened to burnt very quickly.
Flip the chicken just once and reduce the heat to low. Add two tablespoons of unsalted butter to the pan along with a tablespoon of minced garlic. Place the lid on the pan and cook for an additional 5-6 minutes, allowing the garlic butter to melt into the chicken as it finishes cooking. Make sure the internal temperature of the chicken reaches 165°F.
Remove the chicken from the pan and place on a plate. Then, cover the plate with a piece of heavy-duty aluminum foil and set aside.
Add the remaining four tablespoons of butter in the same pan you cooked the chicken and increase the heat to medium. The bottom of your pan might look burnt, but don't worry; all those bits will become incorporated into the sauce while it cooks.
Once the butter has melted, add the rest of the minced garlic and sauté for 1-2 minutes or until fragrant.
Next, add the heavy whipping cream and the rest of the Cajun seasoning blend. Then, using a plastic spatula, stir the spices into the cream to begin making the sauce. Make sure you scrape the bottom of the pan as you're stirring to also incorporate the blackened bits from the bottom of the pan.
Then, switch to a whisk and begin vigorously whisking the sauce so it will emulsify. You should continue to scrape the bottom of the pan as you do this. Whisk the sauce occasionally, for about five minutes, until it thickens and begins to bubble.
In the meantime, cook the fettuccine according to the package directions, minus one minute. Right before the pasta is done, reserve about a cup of the pasta water.
Grate the parmesan cheese and add it to the Alfredo sauce in batches. Whisk the cheese into the Alfredo sauce after each addition, until it has all melted and been incorporated into the sauce.
Add about ½ cup of the reserved pasta water to the sauce. Whisk the sauce until all the water has been incorporated and the sauce is smooth and creamy.
Add the cooked fettuccine and stir the pasta into the sauce until all the noodles are coated.
Uncover the chicken breasts and cut them into ¼-inch slices.
To serve, place the sliced breasts on top of a bed of the Cajun Blackened Fettuccine Alfredo.
Yield 4 servings.