Mix oil, brown sugar, mashed banana, vanilla, milk, and sugar in a bowl.
These cookies will be way better eaten fresh, the day they are made. But they can easily be stored. Place them in the fridge, covered, for up to 2 days, and make sure to let them come to room temperature before enjoying.
Once you remove them from the oven, you can also place some chocolate chips on top of each cookie. I put about 3 chocolate chips on top of each cookie. The bottom of the chocolate chip will melt and stick to the cookie, and it will make your cookies look extra pretty!