Place the chicken breasts in the bottom of the slow cooker.
In a medium bowl, whisk together the heavy cream, chicken broth, garlic powder, Italian seasoning, salt, and black pepper.
Pour the cream mixture over the chicken breasts in the slow cooker.
Cover and cook on low for 3 to 4 hours, until the chicken is cooked through and tender.
Remove the chicken breasts from the slow cooker and shred them using two forks.
Add the Parmesan cheese to the slow cooker and stir until the sauce is smooth and creamy.
Return the shredded chicken to the slow cooker and stir to combine.
Cook the fettuccine pasta according to package instructions until al dente. Drain and set aside.
In a small skillet, melt the butter over medium heat. Add the minced garlic and sauté for 1 minute until fragrant.
Add the garlic butter to the slow cooker and stir well.
Add the cooked fettuccine pasta to the slow cooker and gently toss to coat the pasta evenly with the Alfredo sauce and chicken.
Sprinkle chopped fresh parsley on top before serving.