Peel the apple and remove the core. Cut the apple into small cubes. Put the cubes in a small saucepan with 1 tablespoon of water, sugar and cinnamon and simmer for 2 minutes until the apples have softened.
Finally, put the yogurt, muesli and the apple-sugar mixture in a bowl and stir well. It tastes best when it is slightly warm.
Variants: You can also add chopped nuts, cranberries or raisins.