Preheat oven to 350°F (175°C) and line a baking sheet with parchment paper.

In a large mixing bowl, mash the bananas with a fork or masher until they reach a smooth, liquid consistency.

Stir in the vanilla extract, ground cinnamon, and salt until evenly distributed.

Add the rolled oats to the banana mixture and stir until all oats are thoroughly moistened.

Fold in the chocolate chips and chopped walnuts.

Portion the dough into 12 equal mounds onto the prepared baking sheet using a scoop or tablespoon.

Flatten each mound slightly with the back of a spoon to form a cookie shape, as they will not spread during baking.

Bake for 12 to 15 minutes until the cookies are firm to the touch.

Remove from the oven and allow to cool on the baking sheet for 5 minutes before transferring to a wire rack.