Chicken, leek & cider pie - Good Food Middle East

Ingredients

• 60g unsalted butter
• 60g plain flour
• 250ml dry cider
• 250ml full-fat milk
• 1 tbsp Dijon mustard
• juice ½ lemon
• 2 tbsp crème fraîche
• 3 medium leeks, sliced into rings
• 1 large apple, peeled, cored and sliced
• 500g cooked chicken, torn or cut into pieces
• 50g extra mature cheddar, grated
• 375g puff pastry
• 2 egg yolks, beaten with 2 tsp milk (to make an egg wash)