Put the flour, salt and sugar into a large bowl and stir briefly
Cube the butter and drop it into the bowl. Use your fingers to rub the butter into the dry ingredients until the mixture resembles breadcrumbs
Add 4 tablespoon iced water and mix with a blunt knife. Add a little more water if the dough feels too dry
Use your hands to bring the mixture together and knead briefly and gently until the dough is smooth
Flatten the pastry, wrap in clingfilm and chill for 30 minutes in the fridge
Preheat the oven to 175C/ 325F/ GM3
Roll the pastry out on a floured worktop to a thickness of 2-3mm
Cut out 12 large circles to line your muffin tin holes (see notes for details) and 12 smaller circles big enough to cover the tops. Re-roll the pastry if necessary
Gently push the larger circles into the wells of the muffin tin and spoon the cooled blackcurrant pie filling into each pie - around ⅔ - ¾ full
Use a little beaten egg to wet the rim of the remaining circles and press these onto the pies to form the lid. Ensure there are no gaps between the two layers of pastry
Use a knife to cut a small pattern into the rim of each pie and cut a little slit in the circle to allow air to escape
Brush the top of each pie with beaten egg and sprinkle a little caster sugar over the top
Bake for 20-25 minutes until golden brown
Allow to cool in the tin before removing. Any pies that are stuck in the holes can be loosened with a slim knife
Keep in an airtight container for up to 3 days or freeze