For the cake
You will need 3 x these ingredients to make 6 sponges
4oz (125g) butter, softened and extra for greasing the tins
8oz (225g) plain flour, sifted
5oz (150g) caster sugar
3 medium eggs
1 tsp baking powder (I used Baking powder sachets from Dr. Oetker which are handily 1 teaspoon each!)
pinch of salt
1 tsp vanilla extract
Edible purple food colouring (I used Dr Oetker Ultra Violet Gel Food Colour)
For the icing
1 tsp vanilla extract
3 x 250g tubs of mascarpone
12oz (350g) icing sugar
2 x 20cm round sandwich tins
2 large mixing bowls
A Pretty Serving Plate or Cake stand
A Palette Knife
Rough guide to colouring the sponges
All these amounts are rough measurements as one persons drop is different to some one else's. Add more if you feel that you need it and use this as a rough guide.
1st sponge - 0 food colouring
2nd - 5 drops
3rd - 7 drops
4th - 9 drops
5th - 11 drops
6th - (You want this to be as purple as you can so add as much as you feel makes it the right colour) 20 drops
1.Heat oven to 180'C/160'C Fan/Gas 4. Grease two 20cm round sandwich tins and line with baking paper.
2.Put all the ingredients, apart from the food colouring, for the first two sponges into a large mixing bowl and use an electric whisk to mix them together to a smooth mixture.
3.Weigh the smooth mix into another mixing bowl using electric scales. Then use the same bowl you made the mix in to weigh half of the whole. (For example - 600g halved 300g so 300g for each sponge.)
4.When you have weighed them as equally as you can, put one of the sponges into a prepared tin and smooth down the top. Then add the first amount of food colouring to the other. It is rather an imprecise art using edible colouring but you want to remember that the way it look in raw form is what it will look like as a cooked cake so don't be afraid to make it too colourful. See above for my rough guide to colouring the sponges.
5.Scrape the second mix into the other prepared tin, and get the most out of the bowl with a plastic spatula. Smooth down the top of the second cake and bake the cakes on the same shelf in the oven for 12 minutes or until the sponge is springy and a skewer comes out clean.
6.While the cakes are baking, wash up all the equipment you used for the first batch and dry it ready for the next lot.
7.When the cakes are cooked, turn them out onto a wire rack and peel off the baking paper to make them cool quicker.
8.For the second and third batches of sponges, repeat the recipe above from the beginning and incrementally add more food colouring so that you get a gradient of purple when you put it together.
9. I would suggest making the cakes the day before the party and keeping them in an airtight container or tin as then you have less to think about on the day of the party.
10.On the day of the party, make the icing by putting the mascarpone cheese and vanilla essence into a mixing bowl and using an electric whisk, whisk till smooth. Don't whisk too much as this will make it curdle or become more runny. Sift in the icing sugar and with a spatula fold it into the cheese to make an icing with the consistency of softly whipped cream.
11.To start building the cake, put a dollop icing on the serving plate or cake stand and place the first sponge down on it's head with the domed side down.This gives you a flat surface to work on. Place pieces of greaseproof paper under the cake to keep the serving plate clean. Add a couple of tablespoons of icing on top and smooth down with a palette knife before placing on the next sponge. Keep repeating until you have all the layers on top of each other. Although you want enough icing to make the cakes stick, you want enough to be able to cover the top and sides so be aware of how much you use.
12.Put big spoonfuls of icing on top of the cake and coax it down the sides to cover the entire surface. When you have done it roughly, in the cake business it's called a crumb coat, leave to chill in the fridge for 1/2 hour till it has cooled and it is easier to apply the second layer of icing. Apply the second layer of icing and although the icing is thick, it won't entirely hide the cake underneath.
13.When you have added the final layer of icing, finish with some decorations. I used matching flowers made out of fondant icing.
14.Bring your cake out triumphantly to your waiting guests and when you cut it, let them marvel at the purple sunset inside within.
Fondant flowers are a brilliant decoration to a celebration cake and easier than you think to make!
1.Take a piece of fondant from the block and with you thumb and finger, take off small pieces of fondant and roll into ball. They don't need to be the same size so don't worry about them being the same as each other.
2.When you have a number of balls, take a piece of greaseproof paper and a ball of fondant. Put the fondant on the paper and fold over a corner of paper to cover the fondant. Use your thumb to press the ball flat in a circular shape and the top of your thumb to make the top of the circle thinner.
3.Then take your first petal and roll it gently to make the centre of your flower/rose.
4.Continue the process in step 2 to make petals and add them to your first by swishing (very professional word!) them together.
5.When you have what you think looks like enough petals, leave your flower to dry out overnight or make more to decorate your cake.
6.You can use coloured fondant but I used the gel colour that I used for the cake to make the fondant coloured and it works just as well!