Blueberry Sponge Fingers

1. Preheat the oven to 180°C (200°C/400°F).
2. Add all the ingredients, except the blueberries, to a large bowl and mix using an electric whisk until just combined.
3. Pour the batter into a lined 20cm / 8in brownie tin and spread out evenly.
4. Scatter the blueberries over the batter and gently push them in.
5. Bake on the middle shelf of the oven for 20–22 minutes, or until an inserted knife comes out clean.
6. Lift the cake out of the tin using the baking paper and transfer onto a wire rack to cool.
7. Cut in half down the middle, then into 12 long fingers.