Light, fluffy blueberry sheet cake with dairy-free cream cheese frosting.
Preheat your oven to 180°C/350°F (160°C/325°F for fan and convection ovens). Line an 8x10-inch tin with baking paper.
In a small bowl, mix together the soy milk and apple cider vinegar. Set it aside for 5 minutes to curdle, then mix again briefly. This will act as your vegan buttermilk.
In a large bowl, mix together the flour, bicarbonate of soda and caster sugar. Add your buttermilk along with the oil and vanilla extract. Mix well to make a smooth batter.
Gently fold in the flour-coated blueberries.
Transfer your cake batter to the lined tin and spread it out evenly. Bake for 22-25 minutes, or until a toothpick through the middle comes out clean.
Let the cake cool in the tin for 10 minutes or so then carefully flip it out onto a wire rack and leave to cool completely.
In a large bowl, gently mix all of the ingredients together until smooth. If it's too thick, add a splash of plant-based milk to loosen it. If it's too soft, add some more icing sugar or pop it in the fridge for a while to stiffen.
Spread a generous layer of the frosting over the top of your cooled cake. Let the icing set then cut into 12 squares and enjoy!