Chicken and Mushroom Casserole with Homemade Pastry Top

Ingredients

For the Pastry:
1 1/2 cups flour, plus some to roll out dough
Fine sea salt
1 1/2 teaspoons ground sage, about a 1/3 palmful
3 tablespoons butter, cut into small pieces
1/2 to 2/3 cup whole milk or half-n-half
For the Filling:
2 bone–in, skin-on chicken breasts, about 2 1/2 pounds
2 carrots, peeled and coarsely chopped
2 ribs celery, coarsely chopped

1 onion, quartered
1 large fresh bay leaf
Herb bundle of parsley and thyme
Salt
1 tablespoon EVOO – Extra Virgin Olive Oil
3 tablespoons butter
1 pound button mushrooms, quartered
2 large shallots, finely chopped
1/3 pound green beans, trimmed and cut into 1-inch pieces on a bias
2 rounded tablespoons flour
1/2 cup dry white wine
1/4 cup half-n-half or heavy cream
2 tablespoons Dijon mustard
3 tablespoons fresh tarragon, chopped
A few grates of nutmeg
1 egg, beaten with a splash of water

Yields: 4-6 servings

Preparation

For the pastry, place flour in a mixing bowl and season lightly with salt, about 1/4 teaspoon. Add sage, butter and milk or half-and–half, and combine to form dough.

For the filling, poach chicken in a pot with carrot, celery, onion, bay, herb bundle and salt. Add enough water to just cover the chicken, bring to a gentle boil, reduce heat and simmer about 40 minutes. Remove breast and cool to handle. Strain stock and keep at a low simmer. Remove chicken from bones, discard skin and bones, and pull or chop chicken into bite-sized pieces.

Heat EVOO, 1 turn of the pan, in a large, deep skillet or Dutch oven over medium-high heat. Add butter and melt into oil then add mushrooms and brown until golden, 15 minutes. Season mushrooms with salt and pepper, add shallots and stir 2 minutes more. Add beans and toss together, sprinkle flour over pan, stir a minute more then add wine and reduce 1 minute. Ladle in about 3 cups of warm chicken stock and let thicken a bit. Stir in about 1/4 cup heavy cream, add tarragon and stir in Dijon. Season with a few grates of nutmeg, add chicken and combine.

Preheat oven to 400°F.

Transfer chicken to casserole dish. Roll out dough and trim to fit the casserole. Cut a few slits in dough to allow steam to escape and brush with egg wash. Bake until deeply golden, 30-35 minutes.