How to Make It
In a large saucepan, combine the Basic">http://www.foodandwine.com/recipes/basic-chicken-stock">Basic Chicken Stock, bay leaf, peppercorns and the parsley and thyme sprigs and bring to a boil. Add the chicken breasts and simmer until just cooked through, about 20 minutes. Transfer the chicken to a plate.
Strain the stock, return it to the saucepan and bring to a boil. Add the carrots, celery and pearl onions and cook over moderately high heat until the vegetables are tender, about 10 minutes. Using a slotted spoon, transfer the vegetables to a large plate. Continue to boil the stock until reduced to 3 cups, about 30 minutes.
Meanwhile, melt 1 tablespoon of the butter in a medium skillet. Add the mushrooms and cook over moderately high heat, stirring occasionally, until tender and browned, about 7 minutes. Add the mushrooms to the vegetables on the plate. Remove the breast meat from the bones and pull into 1-inch pieces; discard the skin and bones.
Melt the remaining 4 tablespoons of butter in a medium saucepan. Add the flour and cook over moderate heat, stirring constantly until the roux turns light brown, 4 to 5 minutes. Gradually whisk in the reduced stock and simmer, whisking frequently, until the sauce thickens, 7 to 8 minutes. Remove from the heat and stir in the cooked chicken and vegetables, the chopped parsley, thyme and rosemary and the peas. Season the filling generously with salt and pepper.
Cut the log of Pâte">http://www.foodandwine.com/recipes/pate-brisee">Pâte Brisée into a 5-inch and a 3-inch piece. Cut the 3-inch piece into six 1/2-inch slices. On a lightly floured work surface, roll out each slice of dough 1/4 inch thick; stamp out a neat round from each using a 4-inch biscuit cutter. Fit the rounds into six 4-by-2-inch ramekins. Prick the dough several times with a fork and refrigerate until chilled.
Cut the 5-inch piece of dough into 6 even slices. Roll out each slice 1/4 inch thick; using a 6-inch plate as a template, cut out a neat round from each piece of dough. Transfer the rounds to baking sheets lined with wax paper and refrigerate until firm.
Preheat the oven to 400°. Set the dough-lined ramekins on a baking sheet and bake for 15 minutes, or until the pastry is golden brown. Let the pastry cool slightly, then spoon the chicken and vegetable filling into the ramekins.
Moisten the ramekin rims and cover with the larger rounds, lightly pressing the dough against the ramekins to seal. Brush with the beaten egg and score the tops with shallow parallel marks. Bake the potpies for about 30 minutes, or until the tops are golden brown and the filling is piping hot.
To peel pearl onions, trim the roots slightly and blanch the onions in boiling water for 30 seconds. Let cool slightly, then slip off the skins.