Lemon Curd Cake

4 large egg yolks
2 large eggs
2 3/4 cups sugar
1/2 cup plus 3 tbsp lemon juice
2 cups plain flour - sifted
1/2 tsp salt
1 tbsp baking powder
4 tbsp butter - softened
2 tsp finely chopped lemon zest
6 large egg whites
icing sugar to dust

Whisk together egg yolks, eggs and 1/2 cup sugar.
Stir in 1/2 cup of lemon juice
Cook the mixture over a double boiler, stirring occasionally, for 10 minutes - or until thick.
Strain, place plastic wrap directly onto the surface of the custard and chill until cold.
Mix the cold lemon curd, butter, lemon zest and 3 tbsp lemon juice until well combined.
Stir in the sifted dry ingredients.
Beat the egg whites until frothy and gradually add the remaining 1 1/2 cups sugar.
Beat until soft peaks form.
Fold the meringue into the cake batter.
Put the mixture into a buttered and lined 23cm spring-form pan and bake at 180c for 50-55 minutes.
Cool for 5 minutes in the pan then invert onto a rack to cool completely
Dust the cake with icing sugar to serve.
The cake can be made a day in advance. Store, wrapped in plastic wrap, at room temperature