Heat a drizzle of oil in a large, non-stick pan.
Add the soup mix and fry on a medium heat for 10 minutes, stirring regularly.
Stir in the flour until it disappears (add more oil if it's not being absorbed into the mix) and gently heat through for a couple of minutes.
Slowly add the milk a little at a time, bringing it to the boil each time before adding more and stirring continuously.
Stir in the dijon mustard, grated cheese and season with salt and pepper.
Divide the filling between 4 individual pie dishes - around 11cm wide x 5cm deep.
Cut out four - 12 x 12cm squares from the sheet of pastry.
Place each one on top of the pie dish and press the corners down firmly.
Cut out hearts from the remaining pastry, stick them to the top of the pies with a little beaten egg.
Brush the top of the pies with beaten egg.
Bake in the oven at 190C fan for 25 minutes or until the top is crisp and golden and the pie is cooked through.
