Line the recesses of a muffin tray (for 12 pieces) with paper cups. Mix the pudding powder, 75 g sugar and 100 ml milk. Boil 400 ml milk. Stir in the pudding powder and simmer for about 1 minute while stirring.
Allow to cool, stirring several times.
Mix 150 g butter, 150 g sugar, vanilla sugar and 1 pinch of salt for at least 5 minutes until creamy. Stir in the eggs one by one. Mix flour, starch and baking powder and stir in alternately with 5 tablespoons of milk.
Spread the dough into the moulds. Bake in the preheated oven (electric oven: 175 °C/circulating air: 150 °C/gas: level 2) for approx. 25 minutes. Let them cool down.
Whip 250 g soft butter with the whisk of the hand mixer for approx. 15 minutes until creamy. Stir the pudding briefly. Whip the butter by the spoonful with the hand mixer.
Stir the jam until smooth. Remove the muffins from the paper cups and cut them in half horizontally once. Spread the jam on the lower base. Spread 2/3 of the buttercream as big blobs on top. Place the muffin lid on top and press down gently.
Spread the remaining buttercream on the muffin tops. Cut the cherries into slices or wedges. Decorate muffins with brittle and cherries. Chill for about 1 hour.