Preheat oven to 180C/160C fan assisted. Grease large baking tray with butter and start pastry by adding flour and caster sugar to a big bowl and rubbing the butter and cooking fat into the mixture until its like a breadcrumb texture.

Create a well in the middle and add cold water gradually until pastry looks and feels right. Bring together in a ball then flour surface and hands. Using rolling pin, roll out thinly to cover baking tray then roll back on rolling pin to lift and unload into baking tray. Patch up any holes. You will not need all the pastry for this depending on your baking tray.

Break jam up in a bowl then spread evenly on top of pastry then move onto your sponge cake mixture.

Mix the butter and sugar together well before gradually adding eggs and flour until all combined. Add a little milk to loosen the mixture to allow for easier spreading. Then spread evenly on top of the jam.