Preheat oven to 180℃ on bake.
Beat butter, brown sugar and vanilla essence in a large bowl until light and fluffy. Add in the flour and mix until well combined. The mixture should come together in your hands. Press 3/4 of the mixture into a lined pan roughly 30x22cm. Ensure the base is nice and even. Set aside the remaining mixture for the topping.
To make the apricot filling, place the diced apricots and juice in a pot together and heat until warmed through.
Combine the corn flour and water to make a corn flour slurry.
Add the corn flour slurry to the hot apricots little by little stirring the whole time. If it gets too thick add more juice. If the sauce is still thin, make more corn flour slurry. See video for instructions on this step.
Pour the apricot filling over the base and crumble the remaining base mixture over the top.
Bake for 30 minutes or until golden.
Leave to cool in the tray until cold. Slice and enjoy.