This is adapted from Donna Hay's ingenious 4-ingredient recipe. I just used less banana to more flour ratio so the mixture wouldn't be so soft. They are not very good-looking cookies so you can jazz them up to look more appealing. The cookies have a crispy shell and a soft banana bread middle - a real wholesome treat.

Makes about 15
3/4 c mashed banana (about 2 medium)
3 c almond flour or almond meal (I grind almonds in a coffee grinder then sieve)
1/2 c coconut sugar
1 tsp cinnamon
To sprinkle: 1 tsp cinnamon mixed with 2 Tbsp sugar

Preheat oven to 160C. Line 2 baking trays with baking paper.
Mash the bananas in a bowl then mix in almond flour, sugar and cinnamon. If the mixture is too wet, add some more flour. You could also chill dough in fridge to firm up.
Place large tablespoonfuls onto the trays and shape into flat cookies. They can be placed reasonably close together as they don't spread. Sprinkle with cinnamon mixture. I also added a few coloured sprinkles for kicks. 
Bake for around 25 minutes until cooked through. Leave to cool on the trays for a few minutes before transferring to a wire rack.