Mix the oat flakes with the milk, cover and leave to absorb for approx. 1 hr. Mix the grated apple with the vanilla, leave to infuse for approx. 5 mins. Mix the oat flakes, apple, yoghurt, honey, berries and lemon juice.
Mix the seeds with the sesame seeds and honey, caramelize in an uncoated frying pan for 3-5 mins. while stirring. Spread the mixture on to a sheet of baking paper, leave to cool.
Serve the muesli in 4 portions, sprinkle with the crunchy topping.