for the sponge cake

For the cream, dissolve Maizena in a little milk, stir into hot milk, bring to the boil and allow to cool. Mix the curd, sugar, lemon juice and zest.
Strain the cornstarch mixture and stir into the curds. Whip the whipped cream and fold in carefully.
Cut the sponge cake into three parts, spread the cream on it, assemble it and add sugar if necessary.