at the beginning stir two egg yolks with sugar until creamy. Then heat milk in a saucepan, stir through with the egg yolk-sugar mixture and chill in a water bath. At the same time, fold in gelatin. Whip the whipped cream. Crush blackberries with lemon, egg liqueur and powdered sugar and fold into whipped cream. Finally, mix everything together, fill into dessert glasses and chill in the refrigerator. Then you can garnish with fresh mint and eggnog.