Pour the jar of spinach artichoke pasta sauce evenly over everything, making sure the chicken is mostly covered. Do not add water.
Cover the slow cooker with the lid and cook on LOW for 4–5 hours or on HIGH for 2–3 hours, until the chicken is very tender and easily shreds with a fork.
About 20 minutes before serving, bring a large pot of salted water to a boil on the stove. Add the penne pasta and cook according to package directions until al dente. Drain well.
While the pasta cooks, open the slow cooker and use two forks to shred the chicken right in the sauce. Stir well so the melted cream cheese, spinach, and sauce come together into a smooth, creamy mixture.
Add the drained, hot penne pasta directly into the slow cooker. Gently toss until all the pasta is coated in the creamy spinach artichoke chicken sauce.
