Vegan lemon sheet cake

Heat the oven to 180C/fan 160C/gas 4. Oil and line a deep 24cm x 32cm sheet pan or roasting tin.

Whisk together the chia seeds and 4 tbsp of water in a small bowl. Set aside and leave the mixture to gel.

Put the lemon zest and juice, soy milk, vanilla and olive oil in a high-speed blender or food processor. Blend on high speed until thick and creamy – it should be similar in texture to an aïoli.

Combine the caster sugar and chia seed mixture in a large bowl. Add the blended soy milk mixture, then whisk until smooth.

Sieve the flour into a separate bowl, then add the baking powder and 1 tsp of salt.

Add the flour mixture to the milk/sugar/oil mixture in three stages, mixing gently between each addition. Pour the batter into the prepared tin and put in the oven. Bake for 40 minutes, then remove from the oven and put the baking tray onto a wire rack. Allow the cake to cool completely.

For the glaze, sift the icing sugar into a medium bowl. Squeeze the lemon juice through the sieve to catch any pips. Whisk together well until smooth. Pour the glaze over the cake and spread to cover the surface with the back of a spoon. Sprinkle with poppy seeds, if you like, and leave to set for 15 minutes. Slice into 12 pieces, sprinkle with the lemon zest and serve.