Preheat the oven to 220C and placing the dutch oven, pizza stone or baking tray in the oven to heat up also
Put the flour, salt and bicarbonate of soda in the mixing bowl. Cut up the butter and add. Mix on a low speed until the ingredients have combined.
Add the buttermilk and water and continue to mix until it comes together in a soft dough. Switch the mixer to medium speed and continue for another 2 minutes.
Sprinkle flour on the work surface. Tip out the dough and shape into a round about 2.5 cm thick.
Transfer the dough onto the hot baking tray. Cut down into the dough to make a deep cross on the top.