For the chestnut nougat Christmas tree balls, finely mash the sweet chestnuts with the rum.
Mix butter with 40 g sugar and a pinch of salt until creamy and stir in the egg yolks one by one. Sift flour with baking powder and cornstarch and mix with walnuts, chestnut puree, orange zest and a pinch of cinnamon to the butter cream.
Beat egg whites with remaining sugar until stiff peaks form.
Line a mini muffin baking pan with decorative paper cups and spread batter evenly to just below the rim. Bake in the preheated oven at 175 °C on the middle shelf for about 25 minutes.
Turn the finished muffins out of the pan while they are still hot and let them cool on a cooling rack. Then trim off any batter that sticks out above the pan until smooth.
For the topping, melt the nougat and chocolate in a hot water bath and stir until smooth. Finely crumble the pastry cuttings and mix in. Allow the cream to cool slightly and form balls with an ice cream scoop or ball cutter. Let the balls harden a bit more, then cut them apart in the middle.
Line each nougat dome with colored marzipan, or rolled fondant, shape and attach hangers, and decorate with edible glitter pens, or sugar writing.
Place a decorated nougat dome on top of all mini cupcakes.
Serve the chestnut nougat Christmas tree balls at Christmas time.