Traditional Split Lemon Cake with Filling and Frosting RecipeIngredients:
For the Cake:
350g (2 1/2 cups) cake flour (fine plain flour)
2 tsp baking powder
1/2 tsp baking soda
1/4 tsp salt
200g (1 cup) unsalted butter, at room temperature
300g (1 1/2 cups) granulated sugar
2 large eggs
3 large egg yolks
2 tsp vanilla extract
1 tsp freshly-grated lemon zest
60ml fresh lemon juice
120ml whole milk
For the Filling:
300g (1 1/2 cups) sugar
50g (1/3 cup + 1 tbsp) cornflour (cornstarch)
360ml (1 1/2 cups) hot water
3 egg yolks, lightly beaten
3 tbsp butter or margarine
1 tbsp + 1 tsp freshly-grated lemon zest
80ml (about) lemon juice
For the Lemon Frosting (Icing)
150g (3/4 cup) unsalted butter
700g (3 1/2 cups) icing (confectioners') sugar
2 tbsp double (heavy) cream
2 tsp fresh lemon juice
1/4 tsp vanilla extract
1 tsp finely-grated lemon zest
For the Cake:
Sift together the flour, baking powder, baking soda and salt into a medium-sized mixing bowl.
Add the butter and sugar to a bowl. Cream these ingredients together either with a wooden spoon or electric mixer until pale and fluffy. Add the eggs and egg yolks, one at a time, beating thoroughly to combine after each addition.
Add the vanilla extract and lemon zest then, whilst beating continually, slowly add the lemon juice. Don't worry if the batter seems to curdle, it will fix itself when you add the dry ingredients.
Add 1/3 of the dry ingredients and mix then mix in half of the milk. Add half the remaining dry ingredients followed by the remaining milk. Finally work in the remaining dry ingredients.
Grease the base and sides of two 20cm (8 in) round cake tins and flour them well then divide the cake batter between the tins. Transfer to an oven pre-heated to 170ºC (350ºF) and bake for between 20 and 25 minutes, or until the cakes are cooked through and lightly-browned on top. The cake should be springy in the middle and a skewer inserted into the centre should emerge cleanly when they are ready.
Allow to cool in the tins for 20 minutes then carefully turn the cakes out onto a wire rack to cool completely.
Whilst the cakes are baking prepare the filling. Mix together the sugar and cornflour (cornstarch) in a large pan. Gradually stir in the water then cook over medium heat, stirring constantly with a wire whisk, until the mixture thickens and begins to boil. Continue boiling for 1 minute and take off the heat.
Beat the egg yolks in a heat-proof bowl then, whist beating constantly, add half the boiled mixture in a steady stream. Turn the egg mixture back into the pan and mix with the contents. Gently bring back to a boil and cook for 1 minute then take off the heat before stirring in the butter, lemon zest and enough lemon juice to give your preferred flavour and consistency.
Set aside to cool completely before use.
When the cakes and the filling are cold, split both cakes horizontal to give four layers in all. Place the first layer on a cake stand and top with the filling. Arrange the second layer on top. Continue in this way until all four layers are sandwiched together. Use all the filling mixture for the filling.
Now prepare the lemon icing (frosting). Beat the butter in a bowl until creamy then gradually beat in the icing (confectioners') sugar until completely incorporated. Finally work in the lemon juice, vanilla extract and lemon zest.
Use this buttercream icing to completely cover the top and sides of your cake. When ready, slice into wedges and serve.