In a double boiler, over low heat, melt the chocolate pieces in the water until they are soft. Add the butter, then the peanut butter and mix well. Add the cream and sugar and mix well. Cover the chocolate mixture and refrigerate it until it thickens, but is still pliable.

 

To prepare the truffles, put the powdered cocoa into a bowl. Roll a teaspoonful of the chilled chocolate mixture in the palm of your hand, making a ball. Roll the chocolate ball in the powdered cocoa and store, covered in a cool place.