Sift the flours, bicarbonate of soda and salt into a bowl. Add the butter and rub in with your fingertips until the mixture resembles fine breadcrumbs. Add the spring onion and the herbs and mix well to combine. Make a well in the centre and add the buttermilk or soured milk. Mix with a round-bladed knife to make a soft dough. Turn out on to a lightly floured work surface and knead lightly into a ball. Divide the dough between 8 greased dariole moulds.
Place the dariole moulds on a baking sheet, flatten the dough slightly and dust with flour.
Bake in a preheated oven, 220°C (425°F), Gas Mark 7, for about 25–30 minutes until risen, golden and hollow sounding when tapped underneath. Transfer to a wire rack to cool. For a softer crust, wrap the hot bread in a clean tea towel to cool. Eat on the day it is made.