PREHEAT the oven to 350ºF/180ºC. GREASE a 9-inch (23 cm) round cake pan lightly with oil and line the base with baking paper. SIFT the flour, cocoa, baking powder, baking soda and sugar into a bowl. WHISK the miso, yogurt, oil and water together in a separate bowl. ADD the wet ingredients to the dry ingredients and stir gently to combine. SPOON the mixture evenly into the prepared cake pan. BAKE for 30 minutes. REMOVE from the oven and let cool in the pan for 10 minutes, then turn the cake out onto a wire rack to finish cooling. DUST the top of the cake with confectioners' (icing) sugar, if using.

Variation: For a more decadent version lightly ice the cake with nutella.