Chicken and Leek Pie

WHAT YOU'LL NEED

• 50 g butter
• 25 g flour
• 500 ml semi skimmed milk
• 1 tsp Dijon mustard
• 1 Knorr Chicken Stock Pot
• 4 chicken breast, cut into 4 large pieces
• 2 leeks washed and sliced
• 2 cloves garlic, crushed
• 1 tbsp parsley, chopped
• 1 sheet of ready made shortcrust pastry
• 1 egg, beaten