Best-Ever Chicken and Dumplings

Bring 4 chicken legs (thigh and drumstick), 1 leek, pale-green and white parts only, 1 whole carrot, 1 whole celery stalk, ½ medium yellow onion, chopped, 3 garlic cloves, smashed, 4 sprigs thyme, parsley stems from ½ bunch, 1 bay leaf, 2 tsp. whole peppercorns, and 3 quarts water to a simmer in a large Dutch oven or wide pot over medium-high heat. Cook, uncovered, until chicken is cooked through, 40–50 minutes. Transfer cooked chicken to a plate and let sit until cool enough to handle. Shred chicken into bite-size pieces, discarding skin, bones, and excess fat. Cover shredded chicken with foil to keep warm; set aside.

Strain chicken stock through a fine-mesh sieve into a large bowl; discard solids. Wipe out pot, pour stock back in, and bring to a simmer. Stir in 1 Tbsp. plus 1 tsp. Diamond Crystal or 2 tsp. Morton kosher salt.

Heat ¼ cup plus 1 Tbsp. chicken fat (schmaltz) or unsalted butter, melted, in a large skillet over medium. Cook 3 carrots, chopped into ½" rounds, 3 celery stalks, chopped into ½" pieces, and remaining ½ medium yellow onion, chopped, stirring occasionally, until vegetables are softened but not completely tender, 8–10 minutes; season with salt and freshly ground black pepper. Add ½ cup (63 g) all-purpose flour and cook, stirring, until vegetables are coated, about 1 minute. Scrape vegetable mixture into simmering stock and whisk until liquid is thickened and no lumps remain; continue to cook until vegetables are tender, 10–15 minutes.

Meanwhile, whisk 2 tsp. baking powder, ¼ tsp. baking soda, 1 tsp. Diamond Crystal or ½ tsp. Morton kosher salt, ¼ tsp. freshly ground pepper, and remaining 1 cup (125 g) all-purpose flour in a medium bowl. Whisk ½ cup plus 2 Tbsp. buttermilk and remaining 3 Tbsp. chicken fat (schmaltz) or unsalted butter, melted, in a small bowl. Fold buttermilk mixture into dry ingredients just until dumpling dough comes together (be careful not to overmix or dumplings will be tough).

Add ½ cup heavy cream and reserved chicken to stew and return to a simmer. Drop tablespoon-size portions of dough into stew (don’t worry if they aren’t perfect, they will puff up as they cook). Reduce heat to low, cover, and cook 10 minutes. Uncover and check dumplings for doneness: They should be about 5 times larger and should cover entire surface of stew. To be extra sure, you can remove a dumpling and cut it in half to see if it’s cooked through; the interior should look like a soft dinner roll. If they’re not fully cooked, cover and cook 2 minutes more.

Divide chicken soup and dumplings among bowls, then top with chopped chives. Do Ahead: Chicken soup, without dumplings, can be made 3 days ahead; cover and chill.