Halve the lemon and squeeze it. Peel the banana and coarsely mash it with a fork in a little lemon juice to prevent it from browning. Remove the core from the apple and either peel it or grate it with the skin on a slicer and add it to the lemon banana.
Now stir the quark with sugar and the rest of the lemon juice until smooth. Then stir in the fruit. Pour the nut nougat cream on top and use a fork to distribute it in a wave shape under the quark mixture, creating a swirl effect.