Preheat oven to 180 degrees Celsius/350 degrees Fahrenheit. Prepare your oven proof baking dish by lining it with a thin layer of butter or Spray & Cook.
Beat or whip the sugar and eggs – I find that an electric mixer yields the best results. Beat until thick and pale in colour.
In a small saucer, add the butter and jam together and melt in the microwave for 30seconds. Add the melted butter and sugar to the sugar-egg mixture and mix through. Add the lemon juice and mix again.
Add the flour, baking soda and salt. Beat until well incorporated.
Add the milk and mix.
Pour the batter into your prepared baking dish. Place in the oven (middle rack) and bake for 35-40mins. You want the sponge to be dark brown in colour.