Step 1: Cook the Chicken and Vegetables

• Heat the Oil: In a large frying pan, heat the olive oil over medium heat.
• Cook the Chicken: Add the diced chicken to the pan and cook until browned on all sides. Remove the chicken from the pan and set aside.
• Sauté the Vegetables: In the same pan, add the chopped onion, garlic, carrots, and mushrooms. Cook for about 5-7 minutes until the vegetables are softened.

Step 2: Make the Creamy Sauce

• Add the Flour: Sprinkle the flour over the vegetables and stir to coat. Cook for 1-2 minutes to remove the raw flour taste.
• Add Stock and Cream: Gradually pour in the chicken stock, stirring constantly to avoid lumps. Stir in the double cream and dried thyme, and season with salt and pepper. Let the sauce simmer for a few minutes until it thickens.
• Combine with Chicken: Return the browned chicken to the pan, stir to combine, and cook for another 5 minutes until the chicken is cooked through and the filling is well combined.

Step 3: Cook and Mash the Potatoes

• Boil the Potatoes: In a large saucepan, bring salted water to a boil. Add the chopped potatoes and cook until tender, about 15-20 minutes.
• Mash the Potatoes: Drain the potatoes and return them to the saucepan. Add the butter and milk, then mash until smooth. Season with salt and pepper to taste.

Step 4: Assemble the Pie

• Preheat the Oven: Preheat your oven to 200°C (400°F).
• Fill the Baking Dish: Spoon the chicken filling into a baking dish, spreading it out evenly.
• Top with Mashed Potatoes: Spread the mashed potatoes over the chicken filling, using a fork to create ridges on the surface for a crispy finish.

Step 5: Bake the Pie

• Bake Until Golden: Place the baking dish in the preheated oven and bake for 25-30 minutes, or until the potato topping is golden and slightly crispy.
• Cool Slightly: Allow the pie to cool for a few minutes before serving.