Sear the Chicken: Heat the olive oil in a large frying pan over a medium-high heat. Add the chicken pieces in a single layer (you may need to do this in two batches). Cook for 4-5 minutes, without moving them too much, until the underside turns a deep golden brown and releases easily from the pan. Flip and cook for another 3 minutes until lightly coloured. The chicken should feel firm to the touch but not hard. Transfer to a plate and set aside.

Sweat the Vegetables: Reduce the heat to medium. Add the butter to the pan. Once it melts and begins to foam, add the onion, celery, and carrot. Cook for 6-7 minutes, stirring occasionally, until the onion turns translucent and the carrots begin to soften. You'll notice a sweet, earthy aroma filling your kitchen.

Cook the Mushrooms: Add the sliced mushrooms to the pan. Cook for another 4-5 minutes, stirring every so often. The mushrooms will release their moisture, which will then evaporate, and they will begin to take on a lovely, deep golden colour and a tender, silky texture.

Bloom the Garlic and Spices: Stir in the minced garlic and dried thyme. Cook for 30 seconds until the garlic is fragrant – you'll smell it instantly. Be careful not to let it burn, as it will turn bitter.

Create the Roux: Sprinkle the flour over the vegetables. Stir continuously with a wooden spoon for 1-2 minutes. The mixture will look pasty and dry, and it will smell slightly nutty. This step cooks out the raw flour taste and ensures a smooth sauce.

Build the Sauce: Slowly pour in the chicken stock, a little at a time, while whisking constantly. The mixture will seize up initially, but as you add more liquid and keep whisking, it will become smooth and glossy. Increase the heat to medium-high and bring the sauce to a gentle simmer. You'll see bubbles lazily breaking the surface, and the sauce will thicken enough to coat the back of a spoon.

Finish the Dish: Reduce the heat to low. Stir in the double cream, the reserved chicken (along with any juices on the plate), and the frozen peas. Let everything warm through gently for 5 minutes, stirring occasionally. The sauce should be a beautiful, pale gold, thick and velvety, and the peas will be a vibrant green and tender. Season generously with salt and pepper.

Serve Immediately: Split the warm biscuits in half and place them in shallow bowls. Ladle the creamy chicken mixture over the top, ensuring each serving gets plenty of sauce, chicken, and vegetables. Sprinkle with fresh parsley and serve straight away.