Chicken puff pies

Ingredients

• 1 teaspoon chicken stock powder
• 3/4 cup hot water
• 1 1/2 tablespoon butter
• 1 leek, finely chopped
• 150 gram chopped bacon
• 1/2 teaspoon dried thyme
• 1/2 teaspoon wholegrain mustard
• 1 1/2 tablespoon plain flour
• 3/4 cup milk
• 2 cup shredded cooked chicken
• 1/2 cup frozen baby peas
• 3 sheets frozen flaky puff pastry, thawed
• 1 egg, lightly beaten