To a large bowl, add the bananas and mash until mostly smooth, some chunks are ok.
Add the yogurt, milk, chia seeds, maple syrup and vanilla, and whisk until combined.
Adjust to taste with more maple syrup if desired.
Divide evenly between 4 sealable jars or containers (alternatively store in one large container to dish up as needed).
Chill for at least 15 minutes, or overnight.
To serve, top with sliced banana and whipped cream or Greek yogurt whip and vanilla wafers if using.
