Biscuit-topped Chicken Potpies

INGREDIENTS

2 1/2 cups

reduced-sodium chicken stock

carrots, peeled and finely chopped

medium Yukon Gold potatoes, peeled and finely chopped

stalk celery, finely chopped

4 tbsp

salted butter

medium onion, finely chopped

small cremini or button mushrooms, finely chopped

1 tsp

chopped fresh thyme

5 tbsp

plus 2 cups flour

1 cup

milk

1/4 tsp

freshly grated nutmeg

2 tsp

salt

Freshly ground black pepper

2 tsp

finely chopped flat-leaf parsley

2 1/2 cups

chopped cooked chicken, preferably a mixture of white and dark meat (see Notes)

1/4 cup

frozen sweet peas

1 1/2 tsp

baking powder

1/2 tsp

baking soda

5 tbsp

cold unsalted butter, cubed

1/2 cup

grated sharp cheddar cheese

2 tsp

minced fresh sage

egg

1/2 cup

plus 2 tbsp. well-shaken buttermilk

Egg wash (1 egg yolk whisked with 1 tbsp. milk)