Heat the oil in a small frying pan, add the spring onions and cook gently for 2 minutes until softened. Leave to cool slightly.
Sift the flours, bicarbonate of soda and salt into a large bowl. Stir in the cheese and spring onions. Make a well in the centre, add the buttermilk to the well and gradually stir into the flour. Bring the mixture together with your hands to form a soft, slightly sticky dough.
Tip the dough out on to a lightly floured surface and lightly knead for 1 minute, then shape into a ball.
Place on a lightly floured nonstick baking sheet and flatten slightly. Make a deep cross in the top with a serrated knife. Brush the top with the remaining buttermilk.
Bake in a preheated oven, 200°C (400°F), Gas Mark 6, for 30–35 minutes until the loaf sounds hollow when tapped on the base. Leave to cool on a wire rack. It is best served warm.