Jersey Apple and Blackberry Hand Pies

**Prepare the Pastry:** In a large bowl, whisk together the flour and salt. Add the cold, cubed Jersey butter and rub it into the flour using your fingertips until the mixture resembles coarse breadcrumbs. Gently mix in the mashed Jersey Royal potatoes.

Gradually add the cold Jersey milk, one tablespoon at a time, mixing gently until the dough just comes together. Do not overmix. Form the dough into a disc, wrap in plastic wrap, and refrigerate for at least 30 minutes.

**Prepare the Filling:** In a saucepan, combine the diced Jersey apples, blackberries, caster sugar, cornstarch, lemon juice, and cinnamon (if using). Cook over medium heat, stirring occasionally, until the apples are tender and the blackberries have released their juices, about 5-7 minutes. Remove from heat and let cool completely.

**Assemble the Hand Pies:** Preheat your oven to 200°C (400°F). Line a baking sheet with parchment paper.

On a lightly floured surface, roll out the chilled pastry to about 3mm (1/8 inch) thickness. Use a cookie cutter or a knife to cut out circles or squares, approximately 10cm (4 inches) in diameter.

Place a spoonful of the apple and blackberry filling in the center of each pastry circle. Fold the pastry over to form a half-moon or square. Crimp the edges with a fork to seal tightly.

Brush the tops of the hand pies with the beaten egg and sprinkle with demerara sugar (if using).

Bake for 20-25 minutes, or until the crust is golden brown and the filling is bubbling.

Let the hand pies cool slightly on the baking sheet before serving. Best enjoyed warm.