Preheat oven to 350⁰F (175⁰C).
Place 2 cups of porridge oats in bowl of a food processor. Process until it looks like flour. Add the chickpea flour and pulse to combine. Add the salt, baking powder, baking soda and cardamom; process to combine well.
Transfer to a bowl and add the remaining cup of oatmeal and mix to combine. Add the egg, tahini, vanilla and bananas and beat the mixture until creamy.
Combine banana and flour mixtures. Mix in chocolate chunks. Cover and refrigerate for one hour or longer.
Drop by spoonfuls on baking sheets.
Bake for 15 minutes or until the cookies are puffed up but still very soft: check the underside; if it is browned, remove them from the oven. Cool a few minutes and serve.