Preheat oven to 350 degrees F, and line a small baking sheet with parchment paper or a silicone baking mat.
In a mixing bowl, mash the banana with a fork. Add the maple syrup, vanilla, almond butter, and milk, and whisk until the almond butter is fully incorporated.
Add the remaining ingredients to the bowl, and mix very well. Let the mixture rest for a few minutes. The chia seeds, oats, flour, and raisins will absorb some of the moisture.
At this point if the batter seems too wet and doesn't stick together, stir in another tablespoon of flour or 1 to 2 tablespoons of oats. Scoop up ⅓ cup batter per cookie, and use your hands to form them into a patty shape (your hands will get pretty messy!). Place cookies on the prepared pan. Mix together the cinnamon-sugar topping, if using, and sprinkle onto the cookies.
Bake for 17 to 19 minutes or until firm and set. Cool completely before storing in an airtight container.
Store cookies in an airtight container in the refrigerator for up to 5 days, or freeze for up to one month.