Blueberry Overnight Oatmeal with Chia Seeds

0 Make the Blueberry “Milk”: Add the blueberries to a high-speed blender along with the milk, maple syrup, vanilla, lemon juice, and salt. Blend on high for 45 to 60 seconds, until the blueberries are finely blended into the milk.
1 Mix: Add the oats, chia seeds, and cinnamon and cardamom (if using) to a large bowl and mix well. Pour the blueberry milk into the bowl, then stir until everything is combined. Let sit for at least 5 minutes, to allow the oats and chia seeds to absorb some of the liquid. Then, mix again to incorporate the extra liquid sitting on top.
2 Store & Serve: Transfer the oatmeal to jars or other containers, then store in the fridge for at least 4 hours, preferably overnight. Top as desired and enjoy cold or warm; leftovers will keep in the fridge for up to 5 days.