In a medium bowl, mix together the cocoa powder, granulated sugar and vegetable oil. Whisk in the soy milk and vanilla extract. Set aside.
60 g cocoa powder, 210 g granulated sugar, 80 ml vegetable oil, 60 ml soy milk, 2 teaspoon vanilla extract
In a separate medium bowl, sieve together the flour, baking powder, and salt. Stir the dry ingredients into the wet cocoa mixture using a spatula until a dough forms. Cover the bowl and refrigerate for at least 4 hours or ideally overnight.
130 g plain white flour, 1.5 teaspoon baking powder, ½ teaspoon fine sea salt
Preheat the oven to 175°C. Line a cookie sheet with baking parchment.
Use a small cookie scoop or heaped tablespoon measure to scoop a small ball of dough. Roll in your hands to form a smooth ball.
Into a separate medium bowl, sieve the icing sugar. Roll one ball of cookie dough at a time in the icing sugar before placing on the lined cookie sheet.
30 g icing sugar
Place in the oven for 10 minutes. The cookies will be soft and puffed when removed from the oven. Tap the cookie sheet on the counter gently to deflate the cookies then leave to cool on the cookie sheet for 10 minutes. Transfer to a wire rack to cool before serving.