Place the boneless, skinless chicken breasts into the slow cooker. Add minced garlic, Italian seasoning, salt, and black pepper. Pour in the chicken broth, ensuring the chicken is fully submerged for even cooking and flavor.

Cover the slow cooker with its lid and cook on low heat for about four hours, or until the chicken becomes tender and easily shreds with a fork, developing rich and comforting flavors.

Remove the cooked chicken from the slow cooker and place it on a cutting board. Use two forks to shred the chicken into bite-sized pieces, then return the shredded chicken to the slow cooker.

Stir the heavy cream and grated Parmesan cheese into the slow cooker, mixing well until combined. Add the refrigerated cheese tortellini, ensuring they are submerged in the creamy broth for even cooking.

Cover the slow cooker again and cook on low for an additional 30 minutes, or until the tortellini are tender and fully cooked, allowing the sauce to thicken slightly and become rich and creamy.

Stir the fresh spinach into the slow cooker just before serving. Allow it to wilt for a few minutes, then taste and adjust seasoning if needed. Serve the dish warm and enjoy.