Prep. Preheat the oven to 400°F and line a baking sheet with parchment paper.
Season the chicken. Rub the chicken with salt, pepper, garlic powder, and olive oil until thoroughly coated. Arrange the chicken pieces in a single layer on the prepared baking sheet.
Roast. Bake the chicken for 25-30 minutes or until a meat thermometer inserted into the thickest part of the largest piece reads 165°F.
Rest. Remove the chicken from the oven and let it rest for 5 minutes.
Shred. Transfer the chicken to a cutting board and shred it using 2 forks. Set aside.
For the pasta
Cook the pasta. Meanwhile, fill a large pot with water, add 2 teaspoons of salt to the water, and bring it to a boil. Cook the pasta per the package’s instructions until al dente. Reserve 1-2 cups of pasta water and drain the pasta. Set aside.
Make the sauce. Melt the butter over medium heat in a large saucepan. Add the garlic and saute for 3 seconds. Whisk in the flour and cook for 30 seconds. Gradually whisk in the milk, followed by the heavy cream. Whisk until smooth. Reduce the heat to low and cook the sauce for a minute or two, whisking frequently, until it has thickened to the desired consistency.
Make it cheesy. Stir the parmesan cheese into the sauce followed by the cream cheese. Stir until the cheeses have melted into the sauce.
Season. Taste the garlic parmesan sauce and season with salt and pepper as needed. I usually do a couple pinches of salt and few shakes of ground black pepper.
Put it all together. Stir the pasta and the shredded chicken into the sauce. Stir until the sauce coats every noodle. If the sauce is having a hard time adhering to the noodles, stir in a bit of pasta water to loosen it up.
Serve. Serve the chicken pasta warm, garnished with chopped fresh parsley and additional shredded parmesan cheese, if desired.