This is an excerpt from Le Menagier de Paris
(France, 1393 - Janet Hinson, trans.)
The original source can be found at
David Friedman's website
Chicks may be placed in pastry, back down and breast up, and broad slices of bacon on the breast; and then cover.
Item, in the Lombardy fashion, when the chicks are plucked and prepared, have beaten eggs, both yolks and whites, with verjuice and powdered spices, and moisten your chicks in it: then put in pastry with slices of bacon as above.
Other versions of this recipe:
Pastry of hen (Libro di cucina / Libro per cuoco)