The banana is cut into small pieces and mixed with the other ingredients in a sealable jar. Jam jars are great. If necessary, sugar and / or cinnamon can be added.
Once everything is mixed, the jar is sealed and placed in the refrigerator overnight.
Overnight oats are a great breakfast, I think. They are quick to prepare in the evening and then just have to be taken out of the refrigerator. They are even suitable to take away and can be varied infinitely.