In a bowl, stir the butter or margarine and sugar until frothy. Add the egg and vanilla extract or vanilla sugar and stir until frothy. Stir in flour, baking powder and salt.
Roughly chop the walnuts and white chocolate. Core the apple half and cut into small cubes with an edge length of approx. 0.5 cm.
Add the cinnamon powder to the dough, stir in (possibly a little more or less than indicated, cinnamon is a matter of taste). Add walnuts, chocolate and apple pieces to the batter and stir in evenly.
Remove 1 tablespoon of dough and place in a pile on a baking sheet lined with baking paper. Lightly press. Sprinkle with cinnamon if necessary. The cookies flow a little apart, so leave a little space between the piles. (I usually need two trays for this amount)