Heat the olive oil in a large soup pot over medium heat. When the oil shimmers, add the shallots and cook another 3-5 minutes. Add the celery, carrots, and thyme. Season with salt and pepper. Cook another 5 minutes. Pour in the chicken broth and wine, and bring to a boil over high heat. Cover and cook for 10 minutes.Meanwhile, make the dumplings. In a medium bowl, mix together the mashed potatoes, the flour, baking powder, sage, egg, and a pinch each of salt and pepper until just combined. If the dough feels sticky, add 2-4 tbs additional flour. Bring the soup to a boil over medium-high heat. Drop a heaping tablespoon of the dumpling dough into the soup, adding about 6 dumplings to the soup at a time. Cover, and cook for about 8-10 minutes, until the dumplings are cooked through and puffy. Some of the dumplings may break off into the soup and melt a bit, this is OK and makes the soup creamy.Carefully move the dumplings aside and slide the shredded turkey into the soup. Season to taste with salt and pepper. Divide the soup and dumplings between bowls and serve topped with cheese and pepper. Enjoy!