Mix all the dry ingredients (sift the flours first) in a large bowl. Form a well with your hands.
In a separate container or a measuring jug stir the water with the buttermilk.
Pour the liquid into the bowl, into the formed well and stir with a large wooden spoon until the ingredients form a dough. The mixture will appear quite wet. Leave the dough to rest for 5 minutes.
Preheat the oven to 200 C / 180 C Fan.
Line a baking tray or a skillet with baking parchment and flour it lightly.
Shape the dough into a ball and tip it onto the prepared tray.
Flatten the dough slightly to a circular shape, 18-20 cm in diameter.
Dust with some spelt flour.
You could If you wanted to cut a cross in the top,1 cm deep (make sure you have a very sharp knife to do it).
Bake in the preheated oven for 45 minutes, until a golden crust is formed and the bread is hard on the bottom.
Serve with plenty of butter.