Squeeze the lemon and pour the juice into a coated saucepan. Peel the pears, remove the core and dice the pears and place in the saucepan. Stir several times with a spoon to wet everything with the lemon juice, otherwise the pears will turn dark. Grate the tonka bean, grind the cloves, mix in with the preserving sugar 2: 1 and let steep for 1 hour.
Add the water and slowly bring to the boil while stirring. When the pears are soft, puree the mixture and add the raw marzipan mixture in small cubes. The cooking and stirring continue until the marzipan has dissolved. Make a gelling test and fill the jam into sterile twist-off jars.