Preheat and Brown the Chicken: Preheat your oven to 200°C (180°C fan). Heat the olive oil in a large, heavy-based casserole pan or Dutch oven over a medium-high heat. Season the chicken chunks with salt and pepper, then add them to the pan and cook for 5-7 minutes, until golden on all sides. You don't need to cook them through completely. Remove with a slotted spoon and set aside.

Sauté the Vegetables: Lower the heat to medium and add the onion, carrots, and celery to the same pan. Cook for 8-10 minutes, stirring occasionally, until softened and lightly caramelised. Add the minced garlic and cook for another minute until fragrant.

Create the Sauce: Stir the plain flour into the vegetables and cook for one minute to form a paste (this is called a roux). Gradually pour in the hot chicken stock, stirring constantly to avoid lumps. Once all the stock is incorporated, stir in the double cream, thyme, and Dijon mustard.

Simmer the Filling: Bring the sauce to a gentle simmer and let it bubble for 2-3 minutes to thicken. Return the browned chicken to the pan, add the frozen peas, and season well with salt and pepper. Stir everything together and remove from the heat. If your pan isn't ovenproof, transfer the filling to a 2-litre casserole dish.

Make the Cobbler Topping: In a large bowl, whisk together the self-raising flour, baking powder, and salt. Add the cold, cubed butter. Using your fingertips, rub the butter into the flour until the mixture resembles coarse breadcrumbs. I find that working quickly here prevents the butter from melting. Stir in about three-quarters of the grated cheddar.

Form the Dough: Make a well in the centre of the flour mixture and pour in the milk. Use a cutlery knife to quickly bring the mixture together into a soft, slightly sticky dough. Be careful not to overwork it.

Assemble the Cobbler: Using two spoons or your hands, drop large spoonfuls of the scone dough over the surface of the chicken filling, leaving a little space between each one as they will expand during baking.

Bake to Perfection: Sprinkle the remaining grated cheddar over the top of the scones. Place the dish in the preheated oven and bake for 25-30 minutes, or until the filling is bubbling and the cobbler topping is risen, golden brown, and cooked through.

Rest and Serve: Let the chicken cobbler casserole rest for 5-10 minutes before serving. This allows the filling to settle slightly. Serve hot, straight from the dish.