Heat oven to 180C/gas 5. Grease two 20cm sandwich tins with butter and dust with flour.
In a large bowl beat together the caster sugar, melted butter and eggs until well combined.
Then add the flour, baking powder, grated lemon peel, lemon juice and milk and beat together until you have a smooth batter. If using raw cane sugar, the batter will be a little crunchy as the sugar takes time to dissolve, but the end cake will be nice and fluffy.
Evenly distribute the mixture between the two tins, smoothing the top with a spatula.
Bake for 20-25 minutes or until golden brown. When pricked with a toothpick it should return clean with no uncooked batter.
Turn onto a cooling rack and leave to cool completely.
For the buttercream icing filling, mix the softened butter until creamy and then add the icing sugar and vanilla essence, mixing till well combined.
Spread the buttercream over one of the sponges and layer on top a fine spread of strawberry jam. Carefully place the other sponge on top.
Lastly dust with a little icing sugar on top of the cake before serving. Enjoy!