Step 1: Preheat the Oven

Preheat your oven to 200°C (400°F) and lightly grease a large baking dish or casserole.

Step 2: Make the Chicken Filling

In a large frying pan, heat the olive oil over medium heat. Add the chopped onion, garlic, carrots, and celery. Sauté for about 5 minutes until the vegetables are softened and the onions are translucent.

Step 3: Add the Chicken and Sauce Ingredients

Stir in the flour and cook for 1-2 minutes to remove the raw flour taste. Gradually pour in the chicken stock, stirring continuously until the mixture begins to thicken. Add the cooked chicken, double cream, and thyme (if using). Season with salt and pepper to taste. Let the mixture simmer for 5-7 minutes until it thickens slightly. Pour the chicken mixture into the prepared baking dish.

Step 4: Prepare the Cobbler Topping

In a large bowl, rub the cold butter into the self-raising flour using your fingertips until the mixture resembles fine breadcrumbs. Stir in the pinch of salt, then gradually add the milk to form a soft dough. Turn the dough out onto a floured surface and gently knead it for a few seconds. Roll out the dough to about 2cm thickness and cut out round scones using a pastry cutter.

Step 5: Assemble the Cobbler

Arrange the scone dough rounds on top of the chicken filling in the baking dish. Brush the tops of the scones with the beaten egg to give them a golden glaze when baked.

Step 6: Bake the Cobbler

Place the dish in the preheated oven and bake for 20-25 minutes, or until the scone topping is golden brown and the filling is bubbling around the edges.

Step 7: Serve

Once the chicken cobbler is cooked, remove it from the oven and allow it to cool slightly before serving. This dish is best enjoyed hot and can be served with a fresh green salad or steamed vegetables.