Cut the melon into cubes. Catch any leaking juice and add to the muesli.
Mash about 4 tablespoons of melon meat together with the lemon juice with a fork and stir in the oat milk until smooth. Mix with the flakes, bran, dried blueberries, sunflower seeds and flax seeds. Let everything soak for about 15 minutes.
Stir in the oat cream. If it is still too firm, dilute a little with oat milk or water. Then fold in the melon cubes.