Preheat the oven to 180°C/350°F.
Zest the orange and reserve until needed.
In a 9 inch baking dish add 350 g of apples peeled and cut into 1cm cubes, dried cranberries, the juice of the orange, 2 tbsp water, cornstarch and 1 ½ tbsp of sugar. Mix and reserve until needed.
In a blender or food processor process the oats until you have a fine powder.
Melt the butter and add it to a medium sized bowl along with the eggs, natural yogurt, baking powder, salt, flour, powdered oats, zest of one orange, and 3 tbsp sugar. Mix by hand or with a hand mixer until you have an homogenous cake dough.
Transfer the cake dough on top of the prepared baking dish with fruit and create a smooth surface with the batter. Top with oats and sliced almonds.
Bake for 25-30 minutes, until a cake taster or a knife comes out clean after inserting it into the cake, and the top is golden brown.
Allow to cool for 10-15 minutes (if you can wait) and eat.