Spray slow cooker with cooking spray or lightly coat with olive oil. In a bowl, combine shredded chicken with pesto sauce and onion. Set aside.
In another bowl mix egg, ricotta, spinach, artichokes, salt and pepper, and Parmesan cheese. Set aside.
Pour ½ cup of sauce into the bottom of the slow cooker. Place noodles over sauce, breaking them to fit. They don’t have to be perfect.
Dollop ⅓ of the ricotta mixture over the noodles and spread with a spatula to evenly distribute.
Sprinkle ⅓ of the chicken mixture and layer on top of ricotta mixture. Top with 1 cup of mozzarella cheese and ½ of a jar of sauce.
Repeat with 2 more layers. The final top layer should be a layer of noodles, remaining sauce and cheese only.
Cover and cook on high heat setting for 4 hours, until noodles are tender.