Spray the crock pot with nonstick cooking spray. Add the 1½ pounds chicken breast, ½ cup chicken broth, 21 ounces cream of chicken soup , 1 teaspoon garlic powder, 1 teaspoon onion powder, 1 teaspoon poultry seasoning and ½ teaspoon black pepper. Stir to coat the chicken in the seasonings.
Cover and cook on LOW for 4–5 hours or HIGH for 2–3 hours, until the chicken is fully cooked and tender.
Remove the chicken from the crock pot and shred it with two forks. Return the shredded chicken to the crock pot and stir to mix with the creamy base.
Add the uncooked 8 ounces uncooked ziti pasta and 12 ounces frozen mixed vegetables directly into the crock pot. Stir gently to make sure the pasta is mostly submerged in the sauce. Cover and cook on LOW for 30–40 minutes, or until the pasta is tender, stirring occasionally.
Once the pasta is cooked, pour in the 1 cup heavy cream and stir. Sprinkle 1 cup shredded cheddar cheese over the top, cover, and let it sit for 5–10 minutes until the cheese melts and the sauce is creamy.