Preheat your oven to 180°C and grease and line a 20cm square baking tray.
Add your dairy free butter, light brown sugar and granulated sugar to a large mixing bowl and whisk with an electric whisk until light and fluffy.
Add your egg and continue to whisk. Add your vanilla extract and whisk again.
Add your self raising flour, cornflour and sea salt and mix well. Fold your dairy free chocolate chips into the mixture.
Transfer the mixture to your prepared baking tray, ensuring it's pressed into all the corners. Place in the fridge whilst you make the brownie layer.