Sift the flour, baking powder, salt and bicarbonate of soda into a large mixing bowl.
Whisk the eggs in a jug along with the buttermilk, milk, honey and melted butter.
Whisk the wet ingredients into the dry ingredients until you have a smooth batter, and leave to rest for 30 minutes.
Grease your waffle iron liberally with butter, sprinkle in some of the chopped walnuts, and heat until hot.
Cook the batter in batches until all the batter is used up, keeping the waffles warm as you go.
In a small saucepan gently heat the coconut oil, walnut butter and date syrup to form a sauce, then stir in a pinch of salt.
Serve with the waffles with the sliced bananas, drizzle with the date sauce, and sprinkle with toasted walnuts to finish.