In The Jane Austen Cookbook, Maggie Black and Deirdre Le Faye describe Black Butter as being made of a variety of fruits (some of them dark-coloured such as mulberries, currants and blackberries) supplementing the "less tasty but pectin-rich apples." Fruits frequently used in Black Butter included redcurrants, blackcurrants, gooseberries, strawberries, and apples. (p. 105, The Jane Austen Cookbook).

Here is a recipe from The cook and housekeeper's complete and universal dictionary By Mary Eaton, written in 1822:

Boil a pound moist sugar with three pounds of currants raspberries cherries till reduced to half the Put it into pots covered brandy paper and it will be a pleasant sweetmeat