Preheat the oven to 200C/180C Fan/Gas 6. Line a 2" loaf tin.
In a large bowl or the bowl of a stand mixer, combine the flour, baking powder and sugar.
Make a well in the middle and add the milk, lemon juice, oil and maple syrup. Combine to form a batter.
Coat the blackberries in the cornflour and (very gently) fold into the batter. Pour this into the lined tin and bake 50-55 minutes - check with a skewer at 45 minutes. If getting too brown, either move to the bottom of the oven or cover with foil for remaining bake time. Should be golden brown on top and a skewer should come out clean when inserted.
Once cooked and left to cool on a wire rack (keep it in the tin), make the glaze by combining the icing sugar with maple syrup and milk. It should be thick. Pour over the cake, sprinkle over some berries (optional) and let set.
Once icing has set, slice and serve!
