Combine the chicken, chicken broth, pesto sauce, garlic powder, Italian seasoning, salt and pepper in a slow cooker. Cover and cook on low heat for 7-8 hours or high heat for 3-4 hours.
Remove cooked chicken and shred, using two forks. Return the shredded chicken to the slow cooker and add the tortellini. Cover and cook on high heat for 15 minutes or until the tortellini is al dente.
Add the heavy cream, baby spinach and parmesan cheese. Cover once more until the spinach wilts.
Serve immediately with some more parmesan cheese and crusty bread.