Prepare Crumble mix by mixing plain flour, sugar and butter and crumb them by pinching and grabbing with fingers.
Pre-heat oven to 180C.
Melt margarine completely using microwave for 1min + in big bowl and covered with glad wrap.
Add milk into melted butter and mix with whisk.
Use a 9" dia tray to prepare cake mix. Mix flour and sugar. Add margarine/milk liquid mixture into the dry mixture and gently mix with whisk. Add Vanilla essence and continue to mix with whisk. Finally add and mix in berries or any fruits.
Oil inside of cake tray and coat with some plain flour. Pour cake mix into cake tray.
Spread crumble mix on top of cake mixture and generally level.
Place in pre heat 180C oven. Bake for 45 to 60 min, depending on cake mix thickness.