Begin by crushing the graham crackers into fine crumbs using a food processor or a zip-top bag with a rolling pin.

In a bowl, combine the crushed crackers with a splash of milk, mixing until just slightly moist. Firmly press this mixture into the bottom of a clean jar or container to form a solid crust.

In a separate bowl, mash the ripe banana until smooth, then add in the milk, Greek yogurt, vanilla extract, and maple syrup, whisking together until creamy.

Stir in the rolled or quick oats along with the chia seeds into the banana mixture, mixing until evenly coated.

Carefully pour the oat mixture over the prepared graham cracker crust in the jar and smooth the top.

Cover the jars tightly and place them in the refrigerator for at least 3 hours, preferably overnight.