Line a loaf pan (18x7 cm) with parchment paper and preheat the oven to 180°C.
In a small bowl, combine chopped marzipan and kirschwasser.
Mash with a fork until the kirsch is incorporated and the mixture is smooth. Set aside.
In a bowl, combine yoghurt, oil, sugar, milk, vanilla, and lemon zest.
Add flour, baking powder, and salt. Mix until combined.
Divide dough and add poppy seeds to one half, marzipan mixture to the other half.
Pour half of the marzipan batter into the cake pan, top with half of the poppy seed batter and repeat.
Use a long toothpick or a fork to draw a marbled pattern into the dough.
Bake for 75 minutes or until an inserted toothpick comes out clean. If the top of the cake gets to dark, place a piece of aluminum foil in top. This keeps the cake from browning more.
Remove from pan and let cool completely.
Mix powdered sugar and lemon juice and pour the glaze on top of the cake.
Serve once the glaze has dried.
To keep it fresh, store leftover cake in an airtight container or a sealed plastic bag.