Place the chicken breasts in a single layer at the bottom of the slow cooker.

In a medium mixing bowl, whisk together the pineapple chunks with juice, brown sugar, soy sauce, apple cider vinegar, minced garlic, and ground ginger.

Pour the sauce mixture over the chicken breasts, ensuring they are well coated.

Cover and cook on high for 3 to 4 hours or on low for 6 to 7 hours until the chicken reaches an internal temperature of 165°F.

Remove the chicken from the slow cooker and shred with two forks or slice into bite-sized cubes.

In a small bowl, whisk the cornstarch and cold water to create a smooth slurry.

Stir the slurry into the liquid remaining in the slow cooker and whisk well.

Return the chicken to the slow cooker and cook on high for an additional 15 minutes until the sauce has thickened and coated the chicken.