Add the oats, chia seeds, maple syrup, and milk to a jar. Tightly close the lid and give it a good shake to evenly combine. Put it in the fridge and let it soak and thicken up for at least 3 hours, preferable overnight.
To make the jam: Combine the blueberries, water, and maple syrup in a medium saucepan over medium heat. Cover and let it come to a simmer. Once simmering, stir and mash with a spoon and let it cook for another 5 minutes. Then remove from the heat and stir in the chia seeds. Transfer the jam to a jar and store it in the fridge for up to 5 days.
To assemble the oatmeal: Remove the oats jar from the fridge and top with 2 tbsp peanut butter and 2 tbsp of the jam. Enjoy!