Combine apples, vanilla custard powder, milk powder, sugar and cinnamon in a small zip-lock bag.
Pack crumbled oatmeal cookies separately.
Pour cinnamon apple crisp mixture into the pot and gradually add ½ cup cold water.
Place pot over medium heat. Bring to a boil, stirring all the time.
Reduce the heat and simmer for at least one minute until the custard thickens.
Then, immediately remove from the heat and leave to cool.
Pour crushed cookies over and serve.
