Preheat your oven to 180°C/160°C/Gas Mark 4. Line a 8” square tin with greaseproof paper. Add the lemon juice to the soya milk and stir until the mixture begins to thicken and curdle and set aside.
Place the coconut oil and chocolate into a heatproof bowl and place over a pan of barely simmering water. Stir until the mixture is melted, then set aside to cool.
Mix the flour, Baking Powder, Cocoa Powder and caster sugar together in a large bowl.
Stir in the melted chocolate mixture and then add the soya milk mixture and Vanilla Extract. Stir the mixture together until just combined.
Pour into the prepared baking tin and smooth out to evenly cover the tin, sprinkle the chopped chocolate on top and bake for 30-35 minutes. Once baked the centre of the brownie should have a slight wobble but the side firms, the brownie will firm up as it cools. Leave the cool in the tin.
Once cooled remove the brownie and slice into 9 pieces. Your brownie is now ready to enjoy!