Preheat your oven to 180C (360F).
Mix together self-raising flour, brown sugar, and baking powder in a large bowl. Make sure that there are no lumps. If you don't have self-raising flour then just use normal flour and add 2 tsp baking powder instead of just 1.
Mix together dairy-free milk, sunflower oil, vanilla essence, and apple cider vinegar in a separate bowl.
Combine the dry and wet ingredients and mix well until you get a smooth batter (with no lumps).
Carefully fold in the blueberries.
Line a baking tin with baking paper and grease the sides with vegan butter. Pour the batter into the baking tin and even it out with a spatula.
Bake for 35 min.
Take out of the oven and let cool down thoroughly.
Sprinkle icing sugar on top.
