Rinse and sort blueberries and drain well. Mix berries and jam. Finely chop the chocolate. Crumble meringue shells coarsely.
Stir mascarpone, quark, sugar and vanilla sugar until smooth. Whip cream until stiff and fold in. First meringue and chocolate, then briefly fold in the blueberry mixture. Layer everything in a large bowl or portion glasses.
Cool briefly until serving.