Cook the Chicken
Heat a little oil in a large pot or deep skillet over medium heat. Add the sliced chicken and season with ginger & garlic paste, chilli powder, chicken spice, salt, and black pepper. Cook until golden and fully cooked through, then remove from the pot and set aside.
Sauté the Aromatics
In the same pot, melt the butter. Add the diced garlic, green chillies (if using), and thyme. Sauté until the garlic is fragrant and the thyme begins to release its aroma for about 2 minutes.
Cook the Mushrooms
Add the sliced mushrooms and sauté until they release their moisture and start to brown.
Make the Creamy Base
Sprinkle in the packet of Knorr Cream of Chicken Soup and stir until it forms a thick paste or roux. Gradually whisk in the milk to avoid lumps. Let the sauce thicken slightly, it should coat the back of a spoon.
Add Chicken and Veggies
Return the cooked chicken to the pot, then stir in the frozen mixed vegetables. Let everything simmer together for a few minutes until the mixture is thick and creamy. Stir in the chopped parsley and remove from heat. Allow the mixture to cool slightly before assembling.
Assemble the Pie
Transfer the creamy filling to a baking dish (or keep it in an oven-safe pot). Cover the top with puff pastry. You can place the pastry as a whole sheet, cut into squares, or shape it however you like. Make sure to crimp the edges if sealing fully.
Bake to Perfection
Brush the top of the pastry with beaten egg to get that golden, glossy finish. Bake in a preheated oven at 180°C (356°F) for about 30 minutes, or until the pastry is puffed and golden brown.