1. Preheat your oven to 350°F / 180°C / 160°C Fan / Gas Mark 4. Line and grease three 7 inch cake tins.

2. Mix the ground flax seeds with the cold water and set aside for 5 minutes.

3. In a large bowl, cream together the vegan butter and caster sugar (using an electric/stand mixer if possible). Add the vanilla and mix it in.

4. Add in your flax seed mixture from earlier into the bowl, along with half of the flour and half of the plant-based milk. Fold until it starts to come together.

5. Add the rest of the flour, the baking powder and the rest of the milk and continue gently folding until smooth.

6. Divide the mixture between your 3 cake tins and bake on the middle shelf for 30 minutes until golden brown. If your cakes cannot all fit on the same oven shelf, allow 5-10 minutes extra baking time for those on the lower shelves.

7. Leave the cakes in the tin for 10 minutes, then turn them onto a wire rack and let them cool completely.

For the vanilla frosting:

1. In a large bowl, mix the powdered sugar, vegan butter and vanilla together until smooth. Add the milk in 1 tablespoon at a time, mixing as you go, until you achieve your desired consistency.

To assemble the cake:

1. Place your first (cooled) sponge cake layer onto a cake board or stand. Spread 3 tablespoons of jam over the top, then pipe or spread a thin layer of vanilla frosting on top of the jam.

2. Place the second cake layer on top of the first, spread the jam and frosting over it, then top with the final cake layer.

3. Use a palette knife to smooth the remaining frosting over the top of the cake and along the sides. Clean up any excess at the bottom using a paper towel.

4. While the frosting is still soft, add your sprinkles along the bottom edges by gently "patting" them on in handfuls. Sprinkle some more around the top rim of the cake.

5. If you have any remaining frosting, you can use it to pipe swirls around the top of the cake if desired.

6. Leave in a cool, dry place for 1 hour to allow the frosting to set. Then cut into small pieces and enjoy!