This is an excerpt from A Noble Boke off Cookry
(England, 1468)
The original source can be found at
MedievalCookery.com
To mak cristalle gilly tak whyt wyne that will hold hir colour and boil the fishe ther in and let it stand and serve it furthe.
Other versions of this recipe:
To make crystall gelly (Delights for Ladies)
Recipes with similar titles:
Cristell gely (Recipes from the Wagstaff Miscellany)