Preheat your oven to 350°F and line an 8×8 baking dish with parchment paper or grease it generously.
In a large mixing bowl, mash the overripe bananas until smooth.
Add almond butter, vanilla extract, and ground flax, mixing well.
Incorporate oats, oat flour, baking powder, cinnamon, and sea salt into the mixture until well combined (the batter will be thick).
Fold in the diced apples until evenly distributed.
Transfer the batter to the prepared baking dish, spreading it out evenly.
Bake for 18 minutes, or until a toothpick inserted into the center comes out clean.
Let the bars cool completely before slicing and enjoying!