Place the flour, butter and salt in a bowl. Rub together with your fingertips until the mixture resembles breadcrumbs.
Add the caster sugar, beaten egg and lemon zest. Mix until the dough just comes together.
Tip onto a lightly floured surface and gently knead. Wrap the pastry in cling film and chill for 10–15 minutes.
Scoop the mincemeat into a bowl and stir in the chopped satsumas, apple, lemon zest, cognac and spice.
Heat oven to 220°C/200°C fan/gas 7.
Roll the pastry to about 3mm thick on a lightly floured surface. Using a 10cm round cutter, cut out bases and place them into a muffin tray.
Chill the bases in the tray for 10 minutes to minimise shrinking.
Place one heaped tbsp of the mincemeat mixture into each base. Brush the edges of the pastry with a little beaten egg.
Re-roll the pastry and cut out 7cm lids. Top each pie with a lid, pressing the edges to seal. Cut a small slit or create a decorative pattern in the tops to allow steam to escape.
Brush the tops with beaten egg and sprinkle with caster sugar. Bake for 15–20 minutes until golden brown.
Allow the pies to cool slightly before removing them from the tray. Dust with icing sugar before serving.