Preheat oven to 400 degrees F. Line a baking sheet with foil or parchment. Place the chicken side-by-side and drizzle with about a tablespoon of olive oil. Sprinkle both thighs with a few pinches of salt and pepper. Transfer to the oven to roast for 20 to 25 minutes, until the tops are golden brown and the juices run clear. Remove from the oven and set aside to cool. When they reach closer to room temperature, use two forks to shred the chicken. Discard any scraps and set the shredded chicken aside.
In a dutch oven or medium pot, set over medium heat, add the butter. When melted, add the celery, carrot and thyme. Cook until slightly softened, about 2 to 3 minutes. Mix in the flour and cook for about 1 minute. Next pour in the chicken stock. Bring the mixture to a simmer and then immediately bring it down to medium low; cook for about 6 to 7 minutes, until slightly thickened.
While the soup is cooking, let’s make the dumplings! In a medium bowl, whisk together the flour, cornmeal, baking powder and salt. Pour in the buttermilk and mix until combined.
Give the soup a taste and adjust the salt to your liking and add a bunch of black pepper. I added about 10 turns. Bring the soup up to a gentle simmer and drop tablespoons or ice cream scoops of dumpling dough right onto the boiling point (this will make super fluffy dumplings) and then repeat with the remaining dumpling dough. Cover and cook for about 5 minutes until the dumplings are fluffy and cooked through. Move a dumpling aside and slide the reserved shredded chicken into the pot. Divide amongst bowls and serve!