Preheat oven to 350F.
Mash bananas with a fork in a medium-sized bowl, until a pureed consistency is achieved.
In a food processor or blender, pulse the oats for 10 seconds to break into smaller fragments or blend into oat flour. This helps the cookies hold together. In a pinch, this recipe will also work with whole rolled oats. All options work, but will give the cookies a different texture.
Stir the oats, mashed bananas, and any add-ins to form a batter.
Line a cookie sheet with parchment paper or a silicone mat, scoop out desired amount of cookie dough and press down gently to flatten into cookies.
Bake for 15 minutes or until golden brown.
