Preheat the oven to 190°C / 375°F / Gas mark 5.
Butter 2 x 20cm spring form tins or deep, loose-based tart tins.
Cut one-third of the pastry off each block.
Roll out the smaller pieces of pastry on a floured surface, then cut a circle from each to make the top of the pie – use a tin base as a template.
Roll out two-thirds of the pastry from each block and line the tins, leaving a good amount of excess hanging over the edge.
Mix the sausage meat with the apples, onions and thyme using a food processor.
Divide into 4 portions. Line each pie with 4 slices of ham and spread 1 tablespoon of Dijon mustard over the ham in each pie.
Add a quarter of the sausage meat to each pie and press down to level it.
Add another layer of ham and mustard to each, then the rest of the sausage meat and level off the tops.
Place the pastry lids on top and brush with beaten egg.
Fold the excess pastry over and press gently.
Trim off any excess and make the lid look as attractive as possible.
Brush again with beaten egg and cut a steam hole in the centre.
Bake for 50 minutes or until a skewer pushed in through the steam hole comes out very hot.
Cool in the tin for 15 minutes, then release the sides of the tin and cool completely on a rack (still on the bases).
Serve cold, cut into wedges with pickles and salad.
Or slide off the base and wrap tightly in foil, then cling film and freeze.