Preheat the oven to 175C/350F/Gas Mark 4.
Grease and line a square baking tin with parchment paper & butter.
For the Pastry, add the add all the ingredients into a bowl and work them together into a dough.
For the Crumble, to go on top, separate 120g of the pastry/dough, add the oats, and combine until it resembles a crumble-like texture – add more oats if needed.
Tip the rest of the dough onto a floured surface and roll with a rolling pin until it roughly fits the size of your chosen tin.
Place the dough inthe tin and spread it evenly with your fingers to ensure no breakages.
Place the pastry into the hot oven and bake for 30 minutes or until slightly browned.
For the Filling, add all the ingredients to a bowl and whisk until well combined.
Remove the pastry from the oven after 30 minutes and top with the thawed frozen berries and apple. Pour the filling over the fruit and place into the oven to cook for a further 30 minutes until the filling is set.
Once the filling isset, remove from the oven, allow to cool and cut it into squares.
Serve with yourfavourite hot beverage and enjoy!
