Preheat oven to 180°C conventional (160°fan forced). Lightly grease a 12 cm x 35 cm x 2.5 cm deep loose bottom rectangular flan tin, or tin of similar size.
Base: Beat butter, cream cheese, rind, juice and Chelsea Caster Sugar with an electric mixer until light and creamy.
Sift combined flour and add to creamed mixture and along with ground almonds. Mix until mixture forms a soft dough. Remove from bowl and lightly knead.
Press dough over the base of prepared tin and press up the sides. This builds a recess for the lemon filling.
Bake for 20 minutes or until golden browned. Cool in tin.
Lemon curd: Combine egg yolks, butter, lemon rind and juice and Chelsea Icing Sugar in a small saucepan over low heat, stirring for 7 - 10 minutes or until mixture boils and thickens. Remove from heat. Cool and spread over shortcake base.
Meringue: Beat egg whites with an electric mixer until soft peaks form. Gradually add Chelsea Caster Sugar, one tablespoon at a time, beating until sugar dissolves, add vinegar and continue beating until meringue is thick and glossy.
Spread meringue over lemon filling. Bake for 5-10 minutes or until lightly browned.