Step 1: Prepare the Chicken : Pat chicken breasts dry and season with Cajun seasoning, paprika, salt, and black pepper. Heat olive oil in a large skillet over medium-high heat. Add chicken breasts and cook for 5–6 minutes per side, until golden and cooked through. Remove from skillet and let rest for 5 minutes before slicing into strips.
Step 2: Cook the Pasta : Bring a large pot of salted water to a boil. Cook fettuccine according to package instructions until al dente. Drain and set aside, reserving ½ cup of pasta water.
Step 3: Make the Alfredo Sauce : In the same skillet used for chicken, melt butter over medium heat. Add minced garlic and sauté for 30 seconds until fragrant. Pour in heavy cream and bring to a gentle simmer. Gradually whisk in Parmesan cheese until smooth and creamy. Season with salt, black pepper, and cayenne pepper (if using).
Step 4: Combine Pasta and Sauce : Add cooked pasta to the skillet with the Alfredo sauce. Toss gently to coat, adding reserved pasta water a little at a time if the sauce is too thick.
Step 5: Add Chicken : Slice the cooked Cajun chicken into strips. Place chicken over the pasta or toss it with the pasta and sauce.
Step 6: Serve : Plate the pasta and chicken, spooning extra sauce over the top. Garnish with chopped parsley or green onions and additional Parmesan if desired. Serve immediately while hot.