Prepare the slow cooker by spraying it lightly with olive oil spray.
Place the chicken breasts in a single layer at the bottom of the slow cooker.
Pour in the marinara sauce, garlic powder, onion granules, Italian seasoning mix, paprika, red chili flakes, and chicken broth, ensuring the chicken is fully submerged in the liquid.
Cook on LOW for 4 hours or until the chicken reaches an internal temperature of 165°F.
Carefully remove the chicken from the slow cooker and shred it using two forks.
Return the shredded chicken to the slow cooker and add the tortellini, shredded mozzarella, and heavy cream. Stir well to evenly combine and make sure the tortellini are fully covered by the liquid.
Cover and cook on LOW for an additional 30 minutes, until the tortellini are tender.
Stir in the baby spinach and continue cooking for 10 more minutes.
Finish by stirring in the grated Parmesan cheese, adjusting seasoning to taste, and serve immediately.