Arrange the boneless, skinless chicken breasts in the base of a slow cooker.
Combine the Sauce Ingredients
In a medium mixing bowl, whisk together the Italian dressing, ¼ cup of grated Parmesan cheese, ground black pepper, and minced garlic. Pour this mixture evenly over the chicken.
Add the Cream Cheese
Distribute the cubed cream cheese evenly across the top of the chicken breasts.
Slow Cook the Chicken
Cover and cook the contents on high for approximately 4 hours or on low for 6 hours, until the chicken is cooked through and tender.
Prepare the Pasta
Toward the end of the cooking time, bring a large pot of salted water to a boil. Cook the penne pasta according to the package instructions until al dente. Reserve 1 cup of the pasta cooking water, then drain the pasta.
Shred the Chicken and Combine
Using two forks, shred the cooked chicken directly in the slow cooker. Stir gently to incorporate the shredded meat with the sauce and melted cream cheese mixture.
Add the Pasta
Add the cooked pasta to the slow cooker. Stir gently to combine and coat the pasta evenly with the sauce. If needed, add some of the reserved pasta water gradually to reach the desired sauce consistency.
Serve
Plate the finished dish while warm. Garnish with the remaining Parmesan cheese as desired.
Notes
To make this dish gluten-free, substitute the traditional penne pasta with a certified gluten-free variety. Additionally, verify that the Italian dressing and cream cheese are labeled gluten-free, as some brands may include additives containing gluten.