For the 5-minute apple oatmeal cake from the microwave, grind the oatmeal finely with a stand mixer, for example, and stir well into the water in a glass bowl. Stir in the apple syrup and cinnamon.
Peel, core and grate the apples and mix into the porridge. Now put the whole thing in the microwave at 750 watts for 1 minute. Stir and watch in the microwave for another 1 minute. When the porridge starts to boil/bubble, slowly turn it off and check if it has already solidified.
Sprinkle the 5-minute microwaved apple oat cake with grated apples and cinnamon and serve immediately.