Ingredients
- For the sponge:
- 3 tbsp ground flaxseeds
- 245ml plant milk (I use soya)
- 2 tsp lemon juice or white wine vinegar
- 1 tbsp vanilla extract
- 245ml sunflower oil
- 325g caster sugar
- 345g plain flour
- 1 tsp baking powder
- 1 tsp bicarbonate of soda
- ¼ tsp salt
- For the buttercream:
- 250g dairy-free butter, softened
- 500g icing sugar, sifted
- 1-2 tbsp plant milk
- 2 tsp vanilla extract or 1 vanilla pod, seeds scraped
- To garnish:
- Confetti sprinkles (optional)
For the sponge:
1 Preheat the oven to 200 degrees, or 180 degrees if using a fan oven.
2 Rub or brush a little oil on to a 30x20cm rectangle baking tin and line with parchment paper.
3 Blend the ground flaxseeds with 60ml cold water in a food processor or liquidiser and set aside.
4 In a bowl or jug, mix the plant milk with the lemon juice or white wine vinegar to make a kind of "buttermilk". Put the vanilla extract, oil and sugar in a large bowl and add the flax mix and plant milk, whisking well to combine.
5 Sift in the flour, baking powder, bicarbonate of soda and salt. Fold the dry ingredients into the wet mix until just combined.
6 Spread the sponge mixture in the baking tin and smooth the top. Bake for 40-45 minutes, until well-risen and golden brown, or until a skewer inserted into the centre comes out clean.
7 Leave the sponge to cool in the tin for 10 minutes, before turning out on to a wire rack to cool completely.
For the buttercream:
1 Put the dairy-free butter in a large mixing bowl and add in half of the sifted icing sugar. Cream the butter and sugar together for about two to three minutes until pale and creamy.
2 Sift in the remaining icing sugar and beat again for another two to three minutes until smooth.
3 Add the plant milk and the vanilla extract mix again until well combined. Add another tablespoon of milk to loosen the buttercream if needed.
To assemble:
1 Spread the buttercream on top of the cake and decorate with sprinkles if using.
2 Cut the cake into 12 squares to serve.
