Layer out all the wafer crackers on a chopping board lined with baking paper, and lightly place another board on top to keep the crackers flat. Freeze.
To make the filling, mash the banana until smooth, and stir through the cinnamon. Stir through the coconut oil, until evenly combined, and lastly, whisk through grounded pepita seeds. Freeze, stirring occasionally, until the mix is thick, but still workable.
Remove both the crackers and filling from the freezer. Spoon tablespoons of the filling and dollop onto 10 of the crackers. Using the remaining 10, top the sandwiches, lightly pressing down to ensure the mixture spreads evenly across the bottom cracker. Add more mixture if desired. Freeze.
Break the chocolate into small pieces in a bowl, and microwave for 10 second intervals, stirring each time, until melted, ensuring the chocolate doesn't burn. Set up a work station with a butter knife, spoon and the chocolate.
Remove the sandwiches from the freezer. Spoon chocolate over the top of one, and use the knife to spread evenly across the top, over the sides, and around the edges, making sure everything is covered. It is important to do this step quickly and one sandwich at a time, as the chocolate will begin to set almost straight away.
Repeat for each sandwich, and if there is any chocolate left over, use it to touch up any bare spots. Finally, place the treats back in the freezer to set the chocolate coating completely.