Grease & line two 8"/20cm deep cake tins and preheat your oven to 180ºC/160ºC fan.
Beat together the unsalted butter & caster sugar until smooth - this will take a couples of minutes!
Once combined add the self raising flour, eggs, lemon zest and lemon juice and beat until combined - try not to over beat!
Pour the mixture evenly into the two tins and bake in the oven for 35-40 minutes or until a skewer comes out clean.
Drizzle
Towards the end of baking - in a bowl, mix together your 75ml lemon juice and 75g caster sugar together.
Once the cake is baked, drizzle this over the cakes, whilst still in the tin. Let the cakes cool fully.
Decoration
Beat the unsalted butter for a couple of minutes using the whisk attachment with a stand mixer - doing this will make it nice and smooth!
Once smooth, start gradually adding the icing sugar until it’s all fully mixed in.
Add the lemon juice, and beat for about 5 minutes on a medium-high speed until super light and whipped.
Pipe some buttercream in a circle round the edge of the top of your first sponge, and then add the lemon curd into the middle.
Place the other cake on top, and pipe on the rest of the buttercream however you wish.
Drizzle on some spare lemon curd, and add some sprinkles and enjoy!
Notes
I updated this recipe in May 2017 - the original recipe was 250g of each ingredient, and 5 medium eggs, and the cake was baked for about 25 minutes.
This cake will last in an airtight container for 3-4 days - probably longer as it has so much moisture. I keep mine at room temperature, but sometimes I will keep it in the fridge if I am making it ahead of a party for example - or you can freeze it for up to 3 months!
The layers are thick so if you wanted a more raised cake simply slice the two sponges in to two and have a 4 layer cake!
If you dont have any lemon juice for the decoration, use 2 tsp lemon extract instead.