To make pies that the birds may be alive in them and fly out when it is cut up
Make the coffin (piecrust) of a great pie. In the bottom thereof make a hole as big as your fist... Let the sides of the coffin be somewhat higher than ordinary pies. Fill the pie full of flour and bake it. When baked, open the hole in the bottom and take out the flour. Then put a smaller pie the size of the hole in the bottom of the large pie. Around that small pie put as many small live birds as the outer piecrust will hold just before sending the pie to feast table. When the great lid of the pie is cut open, all the birds will fly out to the delight of the company. And then the guests "be not altogether mocked," the small real pie is served.
This recipe can be found in Reay Tannahill's Food in History , a great source for fantasy writers.