Steps
- Preheat the oven to 425°F / 220°C and line a baking sheet with parchment paper.
- Mix 1¾ cups of finely ground whole-wheat flour, 1¾ cups of all-purpose flour, 1 teaspoon of baking soda, and 1 teaspoon of salt. Rub in 2 tablespoons of cold cubed butter until crumbly.
- Measure 1⅔ cups plus 2 tablespoons of buttermilk, reserving a little for brushing. Gently mix the rest into the flour until a soft, slightly sticky dough forms. Add a little more buttermilk only if dry.
- Gently shape on a floured surface into a 7in / 18cm round, 1in / 2.5cm thick. Transfer to the sheet, cut a deep cross in the top, and prick each quarter. Brush with reserved buttermilk and sprinkle with rolled oats.
- Bake for 15 minutes, then reduce the oven to 400°F / 205°C and bake for 30 minutes, until the base sounds hollow when tapped. Cool on a wire rack.