Prepare the Base: In a large pot, heat 1 tbsp olive oil and 1 tbsp unsalted butter over medium heat. Once the butter is melted, add 1 medium onion (diced), 2 medium carrots (diced), and 2 celery stalks (diced). Sauté these vegetables for about 5-7 minutes, stirring occasionally until they start to soften. Add 3 cloves garlic (minced) and cook for another minute. The mixture should become fragrant.
Build the Broth: Pour in 8 cups chicken broth and add 2 cups cooked, shredded chicken, 1 tsp dried thyme, and 1 bay leaf. Increase the heat to bring the mixture to a simmer. Once simmering, reduce the heat and let it cook gently for 10 minutes. This allows all the flavors to develop.
Make the Dumpling Dough: While the soup is simmering, prepare the dumplings. In a mixing bowl, combine 1 cup all-purpose flour, 2 tsp baking powder, and 1/2 tsp salt. Stir in 2 tbsp unsalted butter (melted) and 1/2 cup milk, mixing until just combined. Be careful not to overmix to ensure the dumplings remain light and fluffy.
Cook the Dumplings: Using a spoon, drop generous spoonfuls of the dumpling dough into the simmering soup. Cover the pot with a lid and let the dumplings cook for 12-15 minutes without lifting the lid. This steaming process is essential for the dumplings to rise and cook through.
Season and Serve: After the cooking time, remove the bay leaf from the pot. Taste the soup and adjust the seasoning with salt and pepper as needed. Serve hot in bowls, garnished with freshly chopped parsley for a pop of color.