1 ½cupssemi-sweet chocolate chips(up to 2 cups if you like lots of chocolate chips, milk chocolate or dark chocolate chips work as well)
Start out your cookie dough with mashing your bananas in a medium sized mixing bowl. Add the vanilla extract and eggs, stir to combine. Add the eggs and mix again, then add the softened butter and break it up while stirring it in. The butter should be small and pea-sized well distributed throughout the wet mixture after the sugars have been added (before combining with the dry ingredients).
Add both the light brown sugar and the white sugar, stir the mixture again. Set aside while you combine the dry ingredients.
In a large mixing bowl, combine the flour, baking soda, ground cinnamon, and salt. Make a well in the center of the dry ingredients, and pour the wet mixture into the well. Stir to combine.
Add the old fashioned rolled oats and stir them in enough so that they are well distributed throughout your cookie dough. Add the chocolate chips in and repeat, stirring them in enough that they are well distributed.
Cover with plastic wrap and refrigerate for about 2 hours (if you are doing a half batch, reduce the time to 1 hour - conversely, if your increasing your batch size also increase the time to refrigerate and chill the dough).
Preheat your oven to 350 degrees F (175 degrees C) and line your baking sheets with parchment paper (or silpat mats, or spray with non-stick cooking spray).
Portion your cookie dough out in heaping tablespoonfuls (you can roll them in your hands to make them nice and round, or simply drop them onto the baking sheet). Allow about 2 inches spacing between each cookie as well as the sides of the baking sheet.
Bake at 350 degrees F (175 degrees C ) for 12-15 minutes, or until the bottom edges are starting to brown. Remove from the oven and allow to cool on the baking sheet for 3-5 minutes before transferring them to a wire cooling rack to cool completely before serving.
*Unused cookie dough can be stored in an airtight freezer bag or container for up to 3-4 months.