To make the dumpling batter, combine the baking mix, milk and garlic powder in a medium bowl. Stir until just combined. Set aside.
In a medium pot, combine the stock, salt, pepper, thyme and bay leaf and bring to a boil. In a small dish, whisk the flour with 1/4 cup water and stir into the chicken stock. Add the chicken and mixed vegetables. Using a tablespoon or an ice cream scoop, drop scoops of the dumpling batter into the boiling stock. Reduce the heat to a simmer and cook, uncovered, for 10 minutes. Cover and cook an additional 10 minutes. Garnish each serving with fresh parsley.