Once the milk has cooled down, add chia seeds and whisk well, leave for 5 minutes and whisk again to remove any clumps that might have formed. Divide the mixture between two serving glasses or jars, leave for 5 minutes and stir again. Place in the fridge. In the morning, top with diced strawberries and blueberries, which you can prepare in the evening as well, and enjoy on the go.