Combine chopped vegetables with butter in heavy bottom pan. Cook until vegetables are softened.
Add flour to partially cooked vegetables and stir to coat. Continue to cook for at least 1 minute.
Next, add chicken broth to flour covered vegetables. Continue to cook over medium heat. Once it boils add milk and chicken.
Make dumpling batter in a medium bowl by whisking dry ingredients and then adding the wet ingredients. Stir to combine.
Use a medium cookie scoop or about 1.5 tablespoons of dumpling batter and drop into broth. Continue until you have a dozen dumplings.
Add lid to pot and simmer for 15 minutes.
Top with thyme leaves and fresh black pepper.