Sift the flour, salt and baking powder together into a large bowl, then make a well in the centre.
Beat the buttermilk and egg together in a jug, add to the well and gradually beat in the flour mixture from around the sides to make a smooth batter. Stir in the sliced bananas.
Heat a large nonstick frying pan over a medium heat. Dip a scrunched-up piece of kitchen paper into the oil and use to wipe over the pan. Drop 3 large tablespoonfuls of the batter into the pan to make 3 pancakes, spreading the batter out slightly with the spoon. Cook for 2–3 minutes until bubbles start to appear on the surface and the underside is golden brown, then flip over and cook for a further 2 minutes. Transfer the pancakes to a baking sheet and keep warm in a low oven while you repeat with the remaining oil and batter.
Serve 3 pancakes per person, topped with the extra sliced banana, sprinkled with the chopped nuts and drizzled with the maple syrup.