In a small saucepan, heat up butter or coconut oil over medium heat. Add the bananas, vanilla, and cinnamon to the heated pan and begin to sauté until they begin to break down and juice out their natural sugars – about 2 minutes.
Add the maple syrup, stir to combine, and cook for another minute, remove from heat.
Inside each jar, place ½ cup oats, ½ teaspoon ground flax, and ¾ cup milk. Divide the cooked bananas evenly over each glass jar
Stir to combine, place the lid on, and refrigerate overnight.