Fill a large pot with water and season it generously with salt. Bring the water to a rolling boil. Once boiling, add the fettuccine pasta and cook according to the package instructions until al dente, usually about 8-10 minutes. Drain the pasta in a colander and set aside, reserving a cup of the pasta water if desired.
Place the thinly sliced chicken breasts in a mixing bowl. Sprinkle the Cajun seasoning over the chicken, ensuring each slice is well coated for maximum flavor.
Heat olive oil in a large skillet over medium heat. Once hot, add the seasoned chicken slices to the skillet. Cook for about 5-7 minutes, turning occasionally, until the chicken is cooked through and golden brown on the outside. Once done, remove the chicken from the skillet and set it aside on a plate.
In the same skillet, reduce the heat to medium-low. Add the finely chopped onion and diced bell pepper. Sauté for 3-4 minutes until the vegetables soften and become fragrant. Then, add the minced garlic and sauté for an additional minute until the garlic is aromatic but not burnt.
Pour in the chicken broth and bring the mixture to a gentle simmer. Stir in the heavy cream, allowing it to bubble softly for 2-3 minutes until the sauce is slightly thickened. Gradually add the grated Parmesan cheese, stirring continuously until the cheese melts completely and the sauce becomes rich and creamy.
Return the cooked chicken to the skillet and add the cooked fettuccine. Gently toss to coat the pasta and chicken in the creamy Cajun sauce. If the sauce is too thick, you can add some reserved pasta water to reach your desired consistency. Taste and season with salt, black pepper, and additional Cajun seasoning if needed.
Remove the skillet from the heat. Serve the delicious Cajun chicken pasta onto individual plates or a large serving platter. Finish with a sprinkle of freshly chopped parsley to add a vibrant pop of color before serving.
Notes
Adjust Cajun seasoning to taste for more or less spice.