Knead the Marzipanrohmasse, the chopped walnuts, and the rum together to combine. Roll out the marzipan mixture to 1/2 inch thickness. Cut out 1 inch squares.

Place chocolate in microwave-safe bowl. Microwave chocolate for 1 minute, then stir to check if it is completely melted. If not, microwave for another minute, and stir again. Repeat until all the chocolate has melted.

Using a toothpick or fork, poke a marzipan square and dunk it in the melted chocolate, making sure the entire marzipan square is covered in chocolate. Let any excess chocolate drip off, then place marzipan square on a plate or cake cooling rack. Immediately place a walnut halve on top of the marzipan square so that it sticks to the chocolate.

Allow covered marzipan squares to cool in the refrigerator so the chocolate hardens.