Preparation time: 25 minutes & cooking time. Difficulty: 2/5.
Cut the mango into cubes. Stir into the yoghurt with the oats.
Grate the apple and stir that in, too. Leave to soak overnight in the fridge.
About 30 minutes before you want to eat the muesli, take it out of the fridge and sprinkle with hazelnuts. Sweeten with agave nectar to taste.