Bring a large pot of salted water to a boil. Add the fettuccine and cook according to package instructions until al dente. Drain and set aside, reserving ½ cup of pasta water in case you need it later.
In a large skillet over medium heat, add the olive oil. Once hot, add the ground turkey. Cook for about 5-7 minutes, stirring occasionally, until fully cooked and browned. Season with salt, pepper, and Cajun seasoning, then remove from the skillet and set aside.
In the same skillet, add the diced onion, and sauté for 2-3 minutes until translucent. Then, add the minced garlic and cook for an additional minute until fragrant.
Stir in the diced red and green bell peppers. Cook for another 5 minutes until they begin to soften.
Pour in the chicken broth and bring to a simmer. Reduce the heat to low and stir in the heavy cream. Let it simmer for about 3-4 minutes until slightly thickened.
Add the ground turkey back to the skillet, stirring to combine. Gradually mix in the Parmesan cheese until melted and creamy. If the sauce is too thick, adjust with a bit of the reserved pasta water.
Add the cooked fettuccine to the skillet, tossing well to coat the pasta in the creamy sauce. Cook for another 2 minutes to heat it through.
Remove from heat and garnish with chopped fresh parsley. Serve immediately while hot.
Notes
Adjust the thickness of the sauce with reserved pasta water if needed.