Using a fork, squash and mash up your berries until they've released their juices. You don't want or need them to be smooth, just nice and juicy. You can use a blender if you prefer, but that's not something I consider a realistic option at 10pm at night. A fork will do fine.
Stir through the chia seeds and maple syrup, put the mixture into a jar or other container and pop it in the fridge until you need it. The chia jam will need an hour or two for the seeds to soak up the liquid and thicken.
When you're ready to use it, check the consistency and add a little water to loosen the jam to the level of thickness you enjoy.
Chia jam will keep for 1-2 weeks in the fridge, but isn't heated or preserved in the same way as regular jam so it won't last indefinitely.
Makes 1 cup (approximate).
For the overnight oats:
Mix everything except the bananas together in a container with a lid, and put in the fridge overnight.
In the morning, check the consistency and add a little more coconut milk if necessary. It's better to start with too little, and add a little more in the morning, rather than starting with too much - which is hard to fix.
Layer chocolate oats and sliced banana, and top it off with chia jam to serve.
Nutrition information estimated - will vary based on the type of milk used.