Mix the millet flakes, chia seeds, nuts and spices in an ovenproof dish and cover with water. If you use frozen berries, you should add them to the mass and let them steep overnight.
In the morning preheat the oven to 150 ° C. Meanwhile, cut the apple and spread it over the mass. If all of the water has been absorbed, pour some more water over the mixture. Put in the oven for 20-30 minutes. If you like, you can season again with cinnamon and eat some yoghurt with it.