Spray a pan with cooking spray and add diced onions with a pinch of salt. Cook over medium-high heat for about 5 minutes until golden and slightly softened.
Add diced chicken and cook for another 5 minutes until browned. Add dried thyme and onion granules and cook for a further 1-2 minutes.
Make up the stuffing with boiling water according to package instructions and set aside.
Add mixed gravy and Worcestershire sauce to the pan along with the stuffing. Stir well and transfer to an ovenproof dish.
Allow filling to cool for a few minutes, then top with puff pastry. Brush with beaten egg.
Bake at 190°C for 25-30 minutes until crispy and golden. Serve and enjoy.
