This is a bit of a mash-up of recipes for lemon drizzle cake and a Swiss buttercream icing recipe from Smitten Kitchen that makes a wonderfully decadent layered birthday cake. The cake is intensely tangy and lemony, and the icing is rich and creamy without being overly sweet (and pipes on beautifully if you’re going for more decorative icing).
This is baked in two 20cm/8 inch square tins, but the same amount of batter will make one larger tray cake in a 30 x 23cm pan – just bake for an extra 5-10 minutes, and forget the icing for more of an afternoon tea style cake.
for the cake –
225g (1 cup) unsalted butter, softened
225g (1 cup) caster sugar
zest of 2 lemons
225g (1 1/2 cups) self-raising flour (or 225g plain flour plus 3tsp baking powder)
for the drizzle –
juice of 2 lemons
75g (1/3 cup) caster sugar
for filling and Swiss buttercream icing –
jar of good lemon curd
170g (3/4 cup) caster sugar
3 large egg whites
275g (approx 1 1/4 cups) unsalted butter, softened
1/2 tsp vanilla extract
Preheat the oven to 160C/140C fan forced. Grease and line two 20cm/8 inch square tins.
Cream together the butter and sugar until fluffy. Beat in the eggs one at a time until well incorporated, then add the lemon zest. With a spatula, fold in the flour. Split the mixture evenly between the two tins – it should be just over 2 cups of batter for each tin. Smooth the surface and bake for 30 minutes, or until a skewer inserted into the centre comes out clean and the edges are just coming away from the side. Leave to cool in the tins for a few minutes, then turn onto a cooling rack.
When you’ve put the cakes in the oven, mix together the lemon juice and sugar for the drizzle in a small bowl. Stir well a few times while the cakes are cooking. When the cakes are cooked, the sugar should have dissolved into the lemon juice.
When the cakes have cooled a little but are still warm, gradually spoon the lemon juice mixture evenly over the tops of the cakes. If the drizzle runs through the cakes, wait for them to cool a bit more before trying again. When the drizzle has been completely spooned on, leave the cakes to cool completely.
When you’re ready to fill and ice the cake, make the buttercream. Put some water into a small saucepan to simmer. Whisk the egg whites and sugar together into a big metal bowl over the saucepan of water. and place the bowl over a small saucepan of simmering water. Whisk until the sugar has completely dissolved – test by rubbing a little of the mixture between your fingers to see if you can feel sugar granules.
Using hand beaters (or having transferred the mixture to the bowl of a mixer), beat or whip until it turns white and approximately doubles in size. Add the vanilla essence. Add the butter a large chunk at a time, beating continuously as you do so. When you’ve finished adding the butter, continue beating until the icing is a thick, smooth, pipeable consistency.
Spread a thick layer of lemon curd on one of the cakes, then cover with a thick layer of buttercream. Place the other cake on top, then ice the whole cake with the remaining buttercream. If you want a precise finish, it may be easier to do a thin crumb layer, then refrigerate the cake for half an hour before covering it with a final layer of icing and any piping.