Preheat your oven to 170ºC/150ºC fan, and line two 8"/20cm cake tins with baking parchment.
In a stand mixer, or a large bowl, beat together the unsalted butter and light brown soft sugar until light and fluffy.
Add in the eggs, self raising flour, cocoa powder and vanilla extract and beat again until combined well.
Split the mixture between the two tins.
Bake the cakes in the oven for 50-60 minutes, or until baked through - check with a skewer to make sure they're done!
Leave the cakes to cool in the tins for 10 minutes, and then take out and leave to cool fully on a wire rack!
Buttercream
Beat the unsalted butter on its own for five minutes, to soften it and loosen it.
Add in the icing sugar and vanilla extract and beat well until smooth and fluffy.
Remove 400g of the buttercream, and colour this using a red food colouring to a deep red colour.
If needed, colour the rest of the buttercream with the white food colouring.
Decorationg
Split the two cakes into four layers in total.
Put the first cake onto a cake board of plate. Add a third of the red buttercream and spread. Repeat with the second and third sponges. Add the final sponge on top.
Using a small amount of the white buttercream, spread and smooth around the cake sides and top for a crumb coat and add to the fridge for at least 30 minutes.
Once set, add more buttercream onto the tops and sides of the cake, and smooth around covering the cake completely in buttercream.
I add the buttercream on using a small angled spatula, and smoothed around the edge with the large metal scraper! You need to make sure there is more buttercream on the sides of the cake than you need, as some will be removed as you smooth it over.
Once finished, put the cake in the fridge again for at least 30 minutes.
Whilst the cake is chilling, heat the oven to 180ºC/160ºC fan, and line a large tray with parchment paper.
Carefully crush the clear sweets to a fine crumb, and pour onto the lined tray in an even spread - and place in the oven for 5 minutes.
Once the sweets have melted, remove the tray from the oven and leave to cool whilst the cake is setting in the fridge.
Once the 'glass' is solid, break carefully into shards (I tapped it with the end of a rolling pin).
Remove the cake from the fridge and carefully insert the shards randomly, like you see in the photos.
Ganache
Add the white chocolate and double cream to a bowl or jug, and microwave until smooth. I do short 10-20 second bursts, stiring well each time.
Once melted, add the food colouring.
Using a small piping bag or a teaspoon, drip the ganache near the shards of the glass, and down the sides of the cake. The more you push over the edge, the further the drip will fall.
Carefully 'splatter' the blood coloured ganache using a pastry brush and flicking it towards the cake... this bit can be messy.
Set the cake in the fridge again for 30 minutes, and then enjoy.