Place the chicken breasts in a single layer in the slow cooker.
In a medium bowl, whisk together the soy sauce, chicken stock, pineapple juice, brown sugar, olive oil, minced garlic and ginger until the sugar is dissolved. Pour the mixture over the chicken breasts, cover the slow cooker and set it to LOW for 4 hours until the chicken is fully cooked.
Using tongs, remove the chicken breasts and discard the bones. Using two forks, shred the chicken breasts and place them in a large bowl.
Pour half of the remaining sauce from the slow cooker in a medium saucepot and discard the other half. Bring the sauce to a boil.
In a small bowl, whisk together the cornstarch with 3 tablespoons water to make a slurry. While the sauce is boiling, whisk in the slurry and continue to boil the sauce until it has thickened and is the consistency of syrup. Pour the sauce over the shredded chicken and toss to combine. Serve the chicken over rice or noodles.