Heat a little oil in a large frying pan. Add the onion and carrot and sauté for 5 minutes.
Add the leek and cook for a further 5 minutes until softened.
Push the vegetables to the edges of the pan if there’s room. Add the chicken and cook for 5 minutes until browned on all sides. If your pan isn’t big enough, remove the vegetables to a plate and cook the chicken separately.
Add the garlic and dried herbs. Stir and cook for a few minutes until fragrant.
Return the vegetables to the pan if removed. Sprinkle over the onion soup mix.
Dissolve the stock cube in the boiling water, then pour into the pan, scraping the bottom to deglaze.
Stir everything together, then add the sour cream and mix until combined. Season well with salt and pepper.
Preheat the oven to 190°C fan bake.
Transfer the filling to a large baking dish and spread out evenly.
Lay the puff pastry over the top, trimming if needed. Brush with milk or an egg wash if you like.
Bake for 30 to 35 minutes until the pastry is golden and cooked through. Serve on its own or with greens or mashed potato.
