Step 1Place the flour, baking powder, salt, baking soda and butter in the bowl of a mixer and mix on low speed until it reaches a sand-like texture.
Step 2Add the buttermilk slowly while mixing. Do not overwork. Form into 2 disks and refrigerate for 1 hour.
Step 3Flour a flat surface and roll out each disk 1/2 inch thick. Trim the dough about 1/2 inch larger than each of 2 (2-quart) casserole dishes that are 2 inches deep. Place each piece of dough on a baking sheet or floured board and poke holes across the top using a fork. Cover with plastic wrap and refrigerate.
Step 1Melt 3 tablespoons of the butter in a deep, heavy-bottomed pot over medium heat. Add the shallots and cook for 2 minutes without browning before adding the chicken backs or wings, carrots, onion, celery, leek, thyme, bay leaf and chicken stock. Bring to a boil and simmer for 45 minutes before removing the carrots. Set the carrots aside, covered. Cook the stock for 30 more minutes. When the carrots have cooled slightly, cut them into small uniform pieces and set aside.
Step 2Add the chicken breasts to the pot and cook at a low simmer until the chicken is cooked through, 18 to 20 minutes. Remove the breasts, cover and set aside. When cool enough to handle, remove the skin and bones and set the meat aside.
Step 3Meanwhile, strain the stock into another pot and discard all of the solid ingredients. Boil the stock at high heat until it is reduced to a syrupy glaze, about 1 1/2 hours. Stir in the cream and cook over low heat for 5 minutes.
Step 4Melt the remaining 1/4 cup of butter and mix in the flour. Whisk the roux into the cream mixture with a whisk and continue stirring while cooking over medium heat, 10 minutes. Strain the sauce into a blender container.
Step 5Blend the sauce until smooth and season to taste with salt and pepper. Set aside to come to room temperature
Step 1Soak the dried mushrooms in cold water for 2 to 3 hours, then rinse several times, changing the water each time until the water remains clear.
Step 2While the mushrooms soak, plunge the asparagus into boiling salted water and cook at a full boil until bright green and crisp-tender, 4 minutes. Remove the asparagus, saving the water, and shock in ice water until cold, 1 minute. Drain and set aside.
Step 3Trim the stem side of the beans, leaving the curly pointed tip intact. Cut the beans in half and cook them in the same boiling water used for asparagus until bright green and crisp-tender, 4 to 5 minutes. Drain and plunge the beans into ice water for 1 minute. Drain and set aside.
Step 4Bring another large pot of water to a boil. Add the sugar then the corn. Boil the corn until tender, 5 to 8 minutes. You can pull an ear out of the water, cut off a kernel or two, and taste for tenderness. Remove the corn, saving the water, and set aside until the corn is cool enough to handle. Cut the kernels off the cob and set aside, covered.
Step 5Plunge the onions into the same boiling water and cook until tender, 2 to 3 minutes. Remove and let cool. Cut away the knob and slide the outside skin off the onion. Set aside.
Step 1Heat the oven to 350 degrees. Combine the Filling, mushrooms, chives and the Sauce and divide between the baking dishes. Lay the Biscuit Crust on top of the filling and sprinkle lightly with flour (this gives the crust a more rustic look).
Step 2Bake until the crust is golden brown and the pies are cooked through, 35 to 40 minutes.