Lemon sponge cake with lemon curd buttercream icing

I bought myself some new cake tins this week and needed to try them out. So I made a very simple lemon sponge cake.

The sponge base is a Victoria sponge (225g each of butter, caster sugar and self-raising flour plus 4 large eggs) with the grated zest of two lemons, divided between 3 lined 20cm cake tins and baked at 180C for 15 minutes.

The icing is an improvised lemon curd buttercream icing. I made the buttercream first from 300g icing sugar and 150g unsalted butter. I then whisked in 300g of lemon curd.
I then layered the cake and icing together. And then ate some.