Put the morello cherries in a saucepan with the liquid (hold back 50 ml of juice and 4 beautiful cherries) and bring to the boil. Mix the cornstarch with 50 ml cherry juice, thicken the cherries with it and allow to cool.
Whip the cream. Mix the low-fat quark with the sugar until smooth. Carefully fold the cream into the quark.
Chop the chocolate.
Layer in four tall glasses as follows: Quark cream - thickened cherries - chocolate - quark cream - cherries - chocolate - quark cream. Garnish the last layer with a cherry and a few chocolate sprinkles.
Enjoy immediately or keep in the refrigerator. If you cover the mug well, the Black Forest mug will still taste good the next day.