Combine the chia seeds, milk, vanilla and maple syrup in a bowl or airtight container and whisk to combine.
Cover and refrigerate overnight, or for at least 5–6 hours, until thickened.
Divide the chia pudding base between two serving jars or bowls.
Process the acai, frozen berries, milk and maple syrup until well combined, thick and creamy. Then spoon acai mixture over chia base and top with fresh berries and puffed millet. Serve immediately.