1Mix together softened butter, granulated sugar (120g) and plain flour (320g) until it forms a dough.
2Split the dough in half and press one half into a lined 8x8" tin.
3Press it down evenly and bake at 190C (170C fan) for about 15 minutes.
4For the filling, add frozen raspberries (230g), raspberry jam (150g), sugar (60g), cornflour (3 tbsp), and lemon juice (1/2 tbsp) to a bowl and mix until it forms a bright red slush.
5Scoop the filling onto the cooled base and spread it out.
6Sprinkle the remaining dough on top.
7Bake again at 190C (170C fan) for about 35 minutes or until golden brown.