Preheat oven to 350°F (180°C). Line a baking tray with parchment paper, slightly oil the paper with oil. Set aside.
Before you start, make sure you are using medium size banana, a medium size banana weight about 118g/4.2 oz unpeeled
In a medium size mixing bowl, mash the banana into a puree, it is ok if there is few lumps
Stir in maple syrup then stir in flour until it form a wet, sticky cookie dough, similar to banana bread dough.
Scoop out dollops of cookie dough on the prepared tray, leaving 1 thumb space between each cookies. The cookie won't expand in the oven.
Slightly spread the dough with the back of spoon into a round cookie shape if desired.
Bake 12 minutes or until slightly golden on the top.
Store in the fridge in an airtight box for up to 3 days.
Gluten-free option : use all-purpose gluten-free flour blendBanana size : you need 2 medium size banana for this recipe. A medium size banana, unpeeled weight 118 grams / 4.2 oz. It represent 1 cup + 1/3 cup mashed banana.