2 lemons, zested and juiced (reserve the zest for the sponge)
100g caster sugar
50g unsalted butter, cubed
1 egg yolk (reserve the egg white for the sponge)
For the lemon sponge:
120g caster sugar plus 2 tablespoons extra for dusting
1 reserved egg white
180g plain flour
120g unsalted butter, melted and cooled
2 lemons, reserved zest only
2 tbsp of icing sugar, to dust
Put the lemon juice, sugar, pinch of salt and butter into a large mixing bowl set over a pan of just simmering water. Don’t let the bowl touch the water. Use a whisk to stir until the sugar dissolves, then add the egg and yolk and whisk vigorously to combine. Cook, stirring constantly, for around 10 minutes until the curd thickens. Strain through a sieve then pour into a jar and leave to cool.
Preheat the oven to 180/160 C fan. Put the lemon curd into a syringe. Generously butter four ramekins and dust the inside with caster sugar. Place in the fridge while you make the batter. Use an electric hand whisk to cream the eggs, egg white and sugar for about 5 minutes until glossy and pale. Sieve in the flour and add the lemon zest and fold through, then add the cooled melted butter and fold until completely mixed. Divide the mixture between the four ramekins - making sure there’s a 2 centimetre gap at the top.
Use a syringe to inject 1 tablespoon of lemon curd into the centre of each cake. Cook for 12 minutes until risen and firm on top. Turn out onto a serving plate and serve immediately with a dusting of icing sugar.