Melt 2 tablespoons butter in a large pot over medium heat. Add onion, carrots, celery, 1 teaspoon kosher salt, pepper and thyme. Sauté for 5 to 7 minutes, or until onions have softened. Add parsley and chicken stock and bring to a boil.

Remove 1/2 cup of the hot stock and whisk in cornstarch, combining until smooth. Pour cornstarch mixture back into the pot and stir to incorporate. Stir in shredded chicken, reduce heat to medium-low and cover.

Melt the remaining 3 tablespoons of butter. Whisk together flour, baking powder,and remaining teaspoon of kosher salt. Stir melted butter and milk in to flour mixture until no dry flour remains.

Dollop spoonfuls of dumpling mixture into simmering soup. Cover and cook for 10 to 15 minutes, or until the dumplings have doubled in size and are cooked through.

Garnish with more chopped parsley, if desired.