Preheat the oven to 450°F (230°C), Gas mark 8. Sift the flour, bicarbonate of soda and salt into a bowl.
Make a well in the centre of the dry ingredients and stir in the cheese and spring onions or scallions, then add the buttermilk. Using a large spoon, mix gently and quickly until you have achieved a nice soft dough. Add a little bit more buttermilk if necessary until the dough binds together without being sloppy.
Knead the dough very lightly on a lightly floured surface and then shape into a round that is roughly 6in (15cm). Place on a non-stick baking sheet and cut a deep cross in the top. Bake for 15 minutes, then reduce the temperature to 400°F (200°C), Gas mark 6 and bake for another 20-25 minutes or until the loaf is evenly golden and crusty. It should sound hollow when tapped on the bottom.
Transfer the cooked soda bread to a wire rack and leave to cool for about 20 minutes. This bread is best eaten while it is still warm. To serve, place the soda bread on a breadboard and cut into slices at the table.
Brown Soda Bread
Use about three-quarters plain flour to one quarter coarse stoneground wholemeal and add two tablespoons of pinhead oatmeal to the mix before adding the buttermilk.