This is an excerpt from Liber cure cocorum [Sloane MS 1986]
(England, 1430)
The original source can be found at
Thomas Gloning's website
For blaunchyd porray. Take thykke mylke of almondes dere And heke hedes þou take with stalk in fere, Þat is in peses þou stryke. Put alle in pot, alye hit ilyke With a lytel floure, and serve hit þenne Wele soþun, in sale, before gode menne.
Other versions of this recipe:
Blanche porrey (Two Fifteenth-Century Cookery-Books)
Blaunche Perreye (Two Fifteenth-Century Cookery-Books)