Serves: 1 loaf
1. To make the bread, first heat your oven to 200°C/Gas Mark 6. Line a baking tray with parchment paper. Put both flours, salt and bicarbonate of soda into a large bowl and mix well.
2. Make a well in the centre and add the chopped roast potatoes and rosemary and the buttermilk. Using your fingers or round bladed knife, draw the flour into the buttermilk. Continue to add the buttermilk until all the flour has been incorporated and you have a sticky dough. You may not need all the buttermilk, different types of flour absorb slightly more or less liquid.
3. Tip the dough onto a floured work surface, shape into a ball then flatten slightly. Place onto a baking tray.
4. Using a large sharp knife mark the loaf into quarters. Cut through the dough but not quite touching the base. Dust the top with flour. Bake for 30-35 minutes until the bread is golden brown and sounds hallow when tapped on the base.
5. Leave to cool on a wire rack.