Preheat the oven to 160 degrees Celsius (320 Fahrenheit) and grease a 23 cm x 13cm (9 x 5 inch)[amazon_link id="B00008W70I" target="_blank" ]Loaf Pan[/amazon_link].
Place the avocado and coconut sugar into the bowl of a food processor and process until smooth. Add the remaining ingredients except the sliced and process until well combined. Pour the batter into the prepared loaf tin.
Place two rows of slices of banana along the middle of the cake until covered. Sprinkle with coconut sugar and bake for 1 hour 20 minutes or until the cake is cooked through in the middle and starts to come away from the sides of the tin. If the top of the cake is browning too quickly cover with foil.
Cool in the tin for 30 minutes before turning out onto a wire rack [amazon_link id="B000HLU84K" target="_blank" cooling rack[/amazon_link] to cool completely.