Prepare the Chicken Base:

Place the chicken, onion, carrots, celery, and garlic in the slow cooker. Add chicken broth, thyme, parsley, salt, and pepper. Stir to combine.

Cook the Base:

Cover and cook on low for 6-7 hours or on high for 3-4 hours, until the chicken is tender and fully cooked.

Shred the Chicken:

Remove the chicken from the slow cooker and shred it with two forks. Return the shredded chicken to the slow cooker.

Thicken the Broth (Optional):

If a thicker broth is desired, whisk the cornstarch into the heavy cream, then stir the mixture into the slow cooker. Let it cook on high for 10-15 minutes to thicken.

Prepare the Dumplings:

In a mixing bowl, combine flour, baking powder, and salt. Cut in the cold butter until the mixture resembles coarse crumbs. Stir in the milk until a soft dough forms.

Cook the Dumplings:

Drop spoonfuls of the dough onto the surface of the simmering broth in the slow cooker. Cover and cook on high for 30-40 minutes, or until the dumplings are puffed up and cooked through.

Serve:

Ladle the chicken, vegetables, and dumplings into bowls. Garnish with fresh parsley if desired and serve hot.