Preheat oven to 350°F (175°C).

In a large bowl, mash the ripe bananas.

Add the butter and brown sugar to the mashed bananas and mix well until combined.

Incorporate the egg whites into the mixture.

In a separate bowl, combine rolled oats, flour, baking soda, and salt.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

Stir in the milk and vanilla extract.

If desired, fold in chocolate chips and/or nuts.

Drop spoonfuls of batter onto a cookie sheet.

Bake for 12-15 minutes, or until golden brown.

Let cool on the baking sheet for a few minutes before transferring to a wire rack to cool completely.