Warm the milk and cream in a bowl to lukewarm. Add yeast and wait five minutes until bloomed. In the meantime, mix the dry ingredients.
Combine the flour, sugar, cardamom, and salt in a large bowl.
Add in the bloomed yeast along with the rest of the ingredients: water and egg. Knead for 10 minutes until a smooth dough forms.
Wait at least one hour until the dough has nearly doubled (it will take longer in a cold kitchen). Put on a clean surface and divide into 12-16 balls. Place on a tray and allow to rise for another 30 minutes to an hour, until slightly puffy.
Preheat the oven to 350 F (180 C). Make the egg wash and brush each bun lightly.
Bake the buns for 12-18 minutes, depending on size. Medium size buns will take 15 minutes.
Make the whipped cream and fill a piping bag. Let the buns cool for five minutes, then cut off the tops. Scoop out 1 tbsp of the dough and replace it with marzipan.
Pipe generous swirls of whipped cream atop the buns, then cover with the top of the bun. Dust with powdered sugar and serve!