For the rough puff pastry, mix the flour and salt together in a bowl. Rub in the chilled butter until the mixture resembles breadcrumbs. Gradually add enough water to form a dough.
On a lightly floured surface, roll out the dough to a rectangle measuring 30cm x 12cm. Grate half of the frozen butter over the bottom two thirds of the dough. Fold down the top third and fold up the top third as if you were folding a letter. Rotate the dough 90 degrees and roll it again into a 30cm x 12cm rectangle.
Grate the remaining frozen butter over the bottom two thirds of the dough. Fold down the top third and fold up the bottom third, again as if you were folding a letter. Rotate the dough 90 degrees. Wrap the dough in clingfilm and freeze for 15 minutes. Remove from the freezer and refrigerate for 15 minutes.
For the filling, cut the apricot halves into 4 pieces. Place the apricots in a frying pan with the sugar, almond extract, cornflour and lemon juice.
Cook over a medium heat for 10 minutes, stirring often, until relatively dry. Remove from the heat and spread out on a plate, to cool. Chill in the freezer for 10 mins.
Heat the oven to 220°C/200°C fan/425°F/Gas 7. Roll out the pastry on a lightly floured surface to a 25 x 37cm rectangle. Cut six 12cm squares out of the pastry.
Divide the apricot filling into 6 and place one portion into the centre of each pastry square. Spread the filling out a little and dot 4 raspberries over each filling.
Brush the edge of one half of each square with some of the beaten egg, then fold over the other side and seal. Crimp the edges with a fork and pierce the top to allow air to escape.
Place on a baking sheet and brush with beaten egg. Bake for 15–20 minutes until dark golden brown.
For the icing, mix the icing sugar with enough lemon juice to make a thick drizzle icing. Drizzle over the turnovers and leave to set.