Biscuit-topped Chicken Potpies

Ingredients

• 1.5 teaspoons double-acting baking powder 
• 0.5 teaspoon baking soda 
• 10 servings pepper black freshly ground
• 0.5 cup buttermilk well-shaken
• 12 small mushrooms finely chopped
• 3  carrots peeled finely chopped
• 1 stalk celery finely chopped
• 2.5 cups roasted chicken dark white cooked chopped (see Notes)
• 1  eggs 
• 1  egg yolk with 1 tbsp. milk)
• 2 teaspoons flat parsley finely chopped
• 5 tablespoons flour 
• 2 teaspoons sage fresh minced
• 1 teaspoon thyme sprigs fresh chopped
• 2.5 cups chicken stock reduced-sodium
• 1 cup milk 
• 0.3 teaspoon nutmeg freshly grated
• 1 medium onion finely chopped
• 0.3 cup peas sweet frozen
• 2 teaspoons salt 
• 4 tablespoons butter salted
• 0.5 cup sharp cheddar cheese grated
• 5 tablespoons butter unsalted cold cubed
• 2 medium yukon gold potatoes peeled finely chopped

Equipment

• bowl
• baking sheet
• sauce pan
• oven
• whisk
• aluminum foil
• rolling pin
• pastry cutter

Directions

1. In a medium saucepan over high heat, bring chicken stock to a boil.
2. Add carrots, potatoes, and celery. Lower heat to medium and cook until vegetables are tender, 5 to 7 minutes.
3. Drain vegetables, reserving stock; set both aside separately.
4. In a large, heavy-bottomed saucepan, melt salted butter over medium heat.
5. Add onion and cook until golden, 6 to 8 minutes.
6. Add mushrooms and cook 5 minutes.
7. Add fresh thyme and 5 tbsp. flour and cook 2 minutes. Slowly add milk, whisking constantly, until combined, then add stock and cook, stirring often, until mixture thickens, 8 to 10 minutes. Season with nutmeg, 1 tsp. salt, and pepper to taste.
8. Add parsley, chicken, cooked vegetables, and peas and divide filling evenly among 6 or 7 ovenproof containers (8 to 10 oz. each), leaving the top 1/4 in. unfilled.
9. Preheat oven to 42
10. To make biscuit topping, sift remaining 2 cups flour with baking powder, baking soda, and remaining 1 tsp. salt. Using your fingers or a pastry cutter, work in unsalted butter to form a coarse meal, working quickly to keep the butter from warming up and melting into the dough. Stir in cheese and sage. In a separate bowl, whisk together egg and buttermilk and add to the flour mixture, stirring gently until a shaggy dough forms.
11. Lightly flour a counter, a rolling pin, and your hands. Divide dough into 2 balls.
12. Roll out first ball to a 1/4-in. thickness, then use a 2 1/2-in. biscuit cutter to cut into rounds, scraping and rerolling dough as needed. Repeat with second ball.
13. Place 3 rounds of dough on each potpie, overlapping as necessary (any unused rounds can be baked on their own as biscuits).
14. Brush dough with egg wash, put potpies on a cookie sheet lined with aluminum foil, and bake until crust is golden brown and filling is bubbling, 17 to 22 minutes.