Preheat your oven to 350°F (175°C).
Line a baking sheet with parchment paper.
Mash the ripe bananas until smooth.
Add the softened butter, Greek yogurt, eggs, and vanilla extract to the mashed bananas and blend until smooth.
In another bowl, whisk together the whole wheat flour, oats, oat bran, baking soda, and salt.
Gradually add the dry ingredients to the wet mixture, mixing until just combined.
Fold in the packed dark brown sugar and chocolate chunks.
Using a cookie scoop, drop the dough onto the prepared baking sheet, spacing them about 2 inches apart.
Bake for 12-15 minutes, or until the edges are lightly golden.
Allow the cookies to cool on the baking sheet for a few minutes before transferring to a wire rack.