Preheat your oven to 350°F (175°C) and line a baking sheet with parchment paper.
Mash the bananas in a large bowl until smooth.
Add the peanut butter and maple syrup to the mashed bananas, and mix well until fully combined.
Stir in the chia seeds, chopped hazelnuts, dried mulberries, chopped dark chocolate, and cinnamon.
Add the oatmeal and mix until everything is well incorporated.
Scoop spoonfuls of the mixture onto the prepared baking sheet, flattening each cookie slightly with the back of a spoon.
Top each cookie with additional chopped dark chocolate pieces and a sprinkle of Maldon leaf salt.
Bake for 15-20 minutes or until the cookies are golden brown and firm to the touch.
Let the cookies cool on the baking sheet for a few minutes before transferring them to a wire rack to cool completely.