Put the cranberries and water in a saucepan, cover, and cook on low heat until
tender and popped.
Pass cranberries through a food mill or press through a sieve
and put the puree back in a saucepan.
Add the butter and sugar, melting gently.
Beat the eggs, then strain them into the fruit. Stir constantly over medium heat
until thickened, being careful not to curdle the mixture (it should coat the back
of a spoon when thickened).
Let cool, then pour into 5 (1/2 pint) jars or any other covered container.