Preheat the oven to 350˚F. Line 2 baking sheets with parchment paper and set aside.
In a large bowl, cream together the banana, lemon juice, butter and sugars. Add int he egg and vanilla, and mix until just combined.
In a separate bowl, mix together the flour, oats, baking soda and cinnamon. Slowly mix the dry ingredients into the wet ingredients until combined.
Fold in the chocolate chips.
Using a medium cookie scoop, scoop the cookie dough onto the prepared baking sheet and bake in the preheated oven for 12 minutes, or until the edges are lightly brown.