Melt the vegan butter in a saucepan and add the water.
Dissolve the caster sugar and brown sugar in the butter-water mixture, heating gently for 3-5 minutes until fully dissolved.
In a separate bowl, whisk together the plain flour, corn flour, baking powder, salt, and cacao powder.
Create a well in the dry ingredients and pour in the wet sugar mixture. Gently fold the wet and dry ingredients together, being careful not to overmix.
Toss the chocolate chips with 1 tbsp of flour to coat them, then fold the chocolate chips into the brownie batter.
Pour the brownie batter into a prepared baking tray and bake at 180°C (360°F) for 32-35 minutes, until a skewer comes out clean.
Allow the brownies to cool completely before cutting into squares.
