Make cake mix according to instructions on packet. Pour into greased and lined Swiss roll tin (base measures 25em x 30cm), bake at 180°C for 30 minutes or until golden brown. Turn onto wire rack to cool; refrigerate until cold. Split cake in half horizontally with sharp knife, spread bottom half of cake with Lemon Butter and cream, replace top. Refrigerate covered for at least 30 minutes. Use sharp serrated knife to cut into diamond shapes. Dust tops with sifted icing sugar just before serving. Decorate with sliced strawberries, if desired.
Lemon butter: Beat eggs and sugar together with fork until well combined. Add lemon rind and juice, water and butter. Place in top of double saucepan or in a bowl over hot water, stir over simmering water for about 10 minutes or until mixture thickens slightly, cool, refrigerate before using.
To freeze: Cakes can be made, cooled, left unfilled wrapped in freezer wrap and frozen for up to 2 months. Note: This recipe is not suitable to microwave.