Combine the chia seeds and oat milk in a bowl, leave to absorb for approx. 5 mins., then stir until smooth. Puree the chia seed mixture in a blender along with all the other ingredients up to and including the coffee powder. Pour into a bowl, cover and chill for approx. 1 hr.
Spoon the chia pudding, yoghurt, granola and berries into the jars in alternate layers.