Cut the chicken into 1-inch bite-sized pieces for even cooking throughout. In a bowl, combine salt, pepper, paprika, garlic powder, and red pepper flakes, then toss the chicken pieces to coat evenly. Transfer the seasoned chicken to your slow cooker and add the garlic parmesan sauce, stirring to combine. Cook on low for 4 hours until the chicken reaches an internal temperature of 165°F. This slow cooking method keeps the chicken incredibly tender and allows the flavors to meld deeply.

About 30 minutes before the chicken finishes cooking, bring a large pot of salted water to a boil and cook the macaroni for just 3 minutes—it should be quite firm since it will continue cooking in the slow cooker. I like to undercook the pasta at this stage because it prevents the final dish from becoming mushy once everything mingles together. Drain the pasta well and set aside.

Once the chicken reaches 165°F, remove it from the slow cooker using tongs or a slotted spoon and shred it using two forks until it reaches your desired texture. Return the shredded chicken to the slow cooker. In a separate bowl, whisk together the softened cream cheese, milk, and dry mustard until smooth and well combined—this prevents lumps from forming when you add it to the hot slow cooker. This step is crucial because cream cheese can seize up if added directly to very hot liquid.

Pour the cream cheese mixture from Step 3 into the slow cooker with the shredded chicken, then add the undercooked macaroni from Step 2 and the freshly shredded Colby Jack cheese. Stir everything together thoroughly to ensure the cheese sauce coats all the pasta evenly. Cook on low for 1 hour, stirring occasionally. The pasta will finish cooking gently in the residual heat while the cheese melts into a creamy, luxurious sauce.

After the hour of cooking, turn off the slow cooker and stir in the freshly grated Parmesan and parsley. I always grate Parmesan fresh rather than using pre-grated because it melts more smoothly and gives you a better texture in the final dish—pre-grated versions contain anti-caking agents that can make the topping grainy. Let it rest for 5 minutes to allow the flavors to fully integrate, then serve immediately while piping hot.