start by softening your dates - place them in a pot with water and bring to boil, allowing to bubble for 5-10 minutes until very soft. allow to cool slightly.
while the dates soften, in a medium-sized bowl, mash your banana.
once the dates are cool, you should be able to remove the skin easily (it should slip off), and then de-pit. place each date in your bowl with the banana.
add the almond butter, and combine everything well, mashing up the dates as you go.
add the egg and vanilla extract and continue mixing.
finally, add the almond flour, coconut flour and baking soda - combine well.
place bowl in the fridge to cool the batter a bit, which will make it easier to manipulate into cookies. i let it sit in the fridge for 2 hours. you can skip this step but it'll be a bit trickier to form the cookies.
line a baking sheet with parchment paper, remove the cookie batter from fridge, and use approx 2 tbsp of batter per cookie, placing each on the tray. wet your wrist/palm of hand to flatten each cookies (the batter will be sticky). repeat on each cookie.
bake in a preheated oven at 350 for 10-12 minutes. allow to cool before removing tray as they will be quite soft. you can store in fridge or freezer. serve to baby in slices they can grasp - the cookies should be large enough to cut into slices as thick as two fingers.