The lemon curd cake is my kind of classic. Make the curd first so it has time to cool completely (warm curd slides straight off a sponge) and keep stirring while it boils or you’ll end up with sweet lemon scrambled eggs. No shame at all in a jar of shop-bought curd if the week has run away from you.
For the lemon curd, place the sugar, cornflour and 450ml of water in a large saucepan and stir until you have a smooth mixture. Stir in the lemon juice, egg yolks and salt. Place over a medium heat and keep stirring while the mixture boils, for about 10-12 minutes. Stir in the lemon zest and butter until the butter has melted, then remove the pan from the heat and allow to cool. If not making your own, use two cups of shop-bought lemon curd.
Preheat the oven to 180C/350F/Gas Mark 4. Grease and line two 21cm springform tins. In a standalone mixer, cream the butter, sugar and lemon zest together until pale and fluffy. Then beat in the eggs, one by one, before adding the vanilla extract and lemon juice.
Using a spatula, fold in the flour and baking powder until you have a smooth mixture. Use a little bit of the milk if you need to loosen the mixture. You want the mixture to be a bit loose.
Divide the mixture into the two springform tins and flatten the tops with a spatula if needed. Bake in the oven for about 20 minutes, until they are nice and golden. When the bases are cooked, take them out and let them cool for a few minutes before you take them out of the tins to cool completely.
While the bases are cooling, prepare the buttercream filling by beating the butter and vanilla extract together in a bowl until light and fluffy. Then add the icing sugar, a little at a time, until it is all incorporated and the mixture is smooth.
To assemble the cake, spread some buttercream on one of the bases before topping with lemon curd, then add the second base and top with another layer of buttercream and lemon curd. Then sprinkle with icing sugar.