Chicken and Biscuits

Ingredients

• 0.8 teaspoon double-acting baking powder 
• 2  bay leaves 
• 0.8 cup buttermilk 
• 1 lb carrots peeled cut into 2" pieces
• 12 ounces celery root peeled cut into 1/2" pieces
• 2 tablespoons crème fraîche sour
• 1 cup wine dry white
• 1 large eggs beaten to blend
• 0.3 cup flour all-purpose
• 2.3 cups flour all-purpose plus more
• 2 tablespoons chives fresh chopped
• 2 teaspoons kosher salt 
• 8 servings pepper freshly ground
• 1  leek white chopped
• 4 cups chicken broth low-sodium
• 1 medium onion chopped
• 1 sprig rosemary 
• 1.5 teaspoons sherry vinegar ()
• 4 sprigs thyme leaves 
• 1.5 pounds chicken thighs bone-in
• 0.3 cup butter unsalted ()
• 0.5 cup butter unsalted cold cut into 1/2" cubes (1 stick)
• 2 tablespoons vegetable oil 

Equipment

• bowl
• baking sheet
• oven
• whisk
• pot

Directions

1. Preheat oven to 400F.
2. Heat oil in a large pot over medium-high heat. Season chicken with salt and pepper. Cook skin side down until skin is golden, 8-10 minutes; transfer to a plate.
3. Carefully drain all but 2 tablespoons fat from pot.
4. Add carrots, celery root, onion, and leek; stir frequently until softened and beginning to brown, 8-10 minutes.
5. Add butter; stir until melted.
6. Add flour and stir constantly until well blended, about 2 minutes.
7. Add wine and 1/2 cup water. Bring to a boil; reduce heat and simmer until liquid is reduced by half, 5-8 minutes.
8. Add chicken, broth, thyme, rosemary, and bay leaves. Bring to a boil; reduce heat. Simmer until chicken is fork-tender, 35-40 minutes.
9. Transfer chicken to a plate.
10. Let cool slightly; shred meat, discarding skin and bones.
11. Return shredded chicken to soup.
12. Add 1 1/2 teaspoons vinegar. Season with salt, pepper, and more vinegar, if desired. DO AHEAD: Soup can be made 2 days ahead.
13. Let cool slightly; chill until cold. Cover and keep chilled. Reheat before serving.
14. Whisk flour, salt, and baking powder in a large bowl.
15. Add butter. Using your fingertips, blend until pea-size lumps form.
16. Add buttermilk, crme frache, and chives. Using a fork, mix until just combined. Gather mixture into a ball and knead in bowl just until a shaggy dough forms, 3 or 4 times.
17. Transfer dough to a floured work surface and pat into a 3/4"- to 1"-thick round.
18. Cut out rounds with a 2" biscuit cutter or small glass. Gather dough and repeat patting and cutting.
19. Transfer to a parchment-lined rimmed baking sheet; brush with egg.
20. Bake biscuits until golden brown, 25-30 minutes.
21. Serve warm or at room temperature. DO AHEAD: Biscuits can be made 8 hours ahead.
22. Let cool completely and store airtight at room temperature.
23. Divide soup among bowls and top with biscuits.