Prepare the Apples: In a medium bowl, toss the diced apples with the lemon juice. This prevents them from browning.

Make the Filling: In a medium saucepan, combine the apples, light brown sugar, plain flour, cinnamon, and nutmeg. Stir to coat everything evenly. Add the unsalted butter and water.

Cook the Filling: Place the saucepan over a medium heat. Cook, stirring occasionally, for 8-10 minutes. The apples should soften but still hold their shape, and the mixture will thicken into a syrupy consistency. Remove from the heat and set aside to cool completely. This is crucial – a warm filling will melt the pastry butter.

Prepare the Pastry: Preheat your oven to 200°C (180°C fan) and line two large baking trays with parchment paper. Unroll your puff pastry sheets. If using a block, roll it out on a lightly floured surface to about the thickness of a £1 coin. Cut the pastry into 8 equal rectangles (approximately 10cm x 15cm each).

Fill the Pies: Spoon about 2 tablespoons of the cooled apple filling onto one half of each pastry rectangle, leaving a 1cm border around the edges. What works best for me is not to overfill them, as tempting as it is! Too much filling will bubble out during baking.

Seal and Crimp: Brush the borders of the pastry with a little of the egg wash. Fold the empty half of the pastry over the filling to create a parcel. Gently press the edges together with your fingers, then use the tines of a fork to crimp and seal the edges firmly.

Chill and Finish: Place the assembled hand pies onto the prepared baking trays. If you have time, pop them into the fridge for 15 minutes to chill. This helps them become extra flaky. Just before baking, brush the tops with the remaining egg wash, then make two small slits in the top of each pie with a sharp knife to allow steam to escape. Sprinkle generously with demerara sugar.

Bake to Perfection: Bake for 20-25 minutes, or until the pastry is deeply golden brown, puffed up, and the filling is just starting to bubble through the vents.

Cool: Let the hand pies cool on the baking tray for 5 minutes before carefully transferring them to a wire rack to cool further. They can be enjoyed warm or at room temperature.