Fluffy coffee flavoured sheet cake with walnuts and cream cheese frosting.
Preheat your oven to 180°C/350°F (or 160°C/325°F if you're using a fan or convection oven). Line an 8x10-inch tin with baking paper.
Mix the coffee granules with 3 tablespoons of boiling water, then set aside to cool.
In a large bowl, mix together the flour, baking soda and sugar.
Add the soy milk to the bowl, along with the cooled coffee, oil, vanilla extract and vinegar. Mix well to make a smooth cake batter, making sure to get any dry bits from the bottom of the bowl.
Add the chopped walnuts and gently fold them in. Pour the batter into your tin and spread it around evenly.
Bake for 25 minutes, or until a toothpick through the centre comes out clean. Leave the cake to cool in the tin for 30 minutes, then flip it out onto a wire rack. Peel off the baking paper and leave to cool completely.
Mix the cream cheese, butter and vanilla together until smooth.
Mix in the icing sugar, a little at a time. Use an electric whisk or stand mixer to whisk for a few minutes until glossy.
Chill the frosting in the fridge for 1 hour before using it, to help it stay firm.
Once chilled, spread the icing over your cooled cake and top with walnut pieces. Cut into 12 pieces and enjoy.