TO MAKE THE PIECRUST:
In the bowl of a food processor fitted with a metal blade, pulse the flour, salt, butter and vegetable shortening until the mixture resembles a coarse meal. Sprinkle with the ice water and pulse until the dough starts to come together, being careful not to let the dough form a ball. Remove the dough and press it into two disks. Cover with plastic wrap and refrigerate while you make the filling.
TO MAKE THE FILLING:
In a large saucepan, sauté the onions and celery in the olive oil over medium heat until soft. Add all the vegetables, and the chicken, turkey or ham, and set aside. In a separate saucepan, melt the butter over medium heat. Whisk in the flour and cook for 2 to 3 minutes. Slowly whisk in the stock until the sauce is smooth. Bring to a boil, whisking constantly. Reduce the heat and simmer, stirring occasionally, for 5 to 7 minutes. Add the pepper and salt. Pour the sauce over the meat and vegetables. Then pour the mixture into 10 individual ovenproof bowls or two 9-inch pie pans. Preheat the oven to 400 degrees. Roll out the piecrust on a lightly floured surface. Cover the 10 (or two) pies with the dough. Use a cookie cutter to cut bunnies out of scraps of piecrust. Lightly brush the egg onto the piecrusts and place a bunny on top. Bake for 20 to 40 minutes, or until the crust is browned and the filling bubbles. It's a good idea to place a cookie sheet below the pies to catch any drips. Makes 10 to 12 servings.