Finely mash the banana with a fork. Mix with the yogurt. Wash the apple, do not peel it, remove the core and chop it up. Add to the yogurt with the flakes and sunflower seeds. Mix everything well. In this version, it can be kept cool for a day. Great as a second breakfast at work. Only gets a little brown because of the banana. Depending on the taste and season, this muesli can be modified as desired. The above ingredients are the basis / winter variant. Pears, nectarines, all kinds of berries, grapes, apricots, plums, pumpkin seeds and melon all taste delicious. If there is a lot of fruit, I always add a second cup of natural yoghurt. You may then also increase the amount of flakes. I find that this granola doesn`t need to be sweetened. The banana gives it a natural sweetness.