Run a knife around the edges and slice into large cubes. Fill a cup halfway with cold milk and add simple syrup (1:1 water and sugar boiled until sugar is melted and cooled) or agave syrup to taste. I like to make this drink a bit sweet, but add as much as you like. Add coffee jelly cubes and top with an optional shot of espresso. Add a few ice cubes if you want to make this drink cold.