Peel the banana, cut off 2 slices for decoration and put aside. Cut the rest of the banana roughly into pieces. Puree buttermilk and banana. Put quark in a bowl and stir in the banana buttermilk.
Roughly chop trail mix. Put half of the quark in a glass, sprinkle with half of the trail mix and sprinkle with 1/2 teaspoon honey. Then add the remaining quark and nuts and sprinkle with the remaining honey.
Decorate with banana slices.