Prepare the chicken: Place 1.5-2 lbs boneless, skinless chicken breasts at the bottom of your slow cooker, ensuring they are spread out evenly.
Make the sauce: In a medium mixing bowl, combine 1 bottle Olive Garden Italian dressing, 1 cup freshly grated Parmesan cheese, ½ tsp black pepper, and 4 cloves garlic, minced. Stir well until the cheese is well incorporated.
Combine with chicken: Pour the sauce mix over the chicken, ensuring the breasts are fully coated.
Add cream cheese: Top the chicken and sauce with 1 block full-fat cream cheese, allowing it to melt and integrate during cooking.
Cooking time: Cover the slow cooker and set it to cook on high for 4 hours or on low for 6 hours, until the chicken is tender and easily shredded.
Cook the pasta: Approximately 30 minutes before the chicken is done, cook your 16 oz penne pasta according to package directions until al dente. Drain and set aside.
Shred the chicken: Once cooked, use two forks to shred the chicken directly in the slow cooker, mixing it with the creamy sauce until well combined.
Add pasta: Gently fold the cooked penne into the chicken and sauce mixture until all the pasta is coated with the creamy sauce.
Serve: Serve the pasta warm, garnished with additional Parmesan cheese if desired for added flavor.