Put the apples in a shallow saucepan with the water and cook until just soft. Sprinkle the cinnamon over and gently mix in. Do a taste test and add sweetener if required. Set aside to cool.
In a glass or pot, sprinkle a layer of oats at the bottom. Then add a layer of apples. If you want to see the layers then be more careful with your layering. If not, just layer away. Cover the apples with yogurt, then repeat.
You can be decorative with the final layer (to make it look pretty), or just add fill the layer up.
Either, eat immediately or allow the oats to soften slightly by placing in the fridge until required. Enjoy!