Prepare the Chicken: Slice each chicken breast horizontally to create two thinner cutlets. Place them between two sheets of cling film and pound them gently with a meat mallet or rolling pin until they are about 1cm thick. This ensures even cooking and tenderness. In a shallow dish, combine the plain flour, dried oregano, garlic powder, onion powder, salt, and black pepper. Dredge each chicken cutlet thoroughly in this seasoned flour mixture, ensuring it's evenly coated. The chicken should look pale and dusty all over.

Sear the Chicken: Heat 2 tablespoons of olive oil in a large, heavy-bottomed frying pan or skillet over medium-high heat. Once the oil shimmers slightly and you can hear a gentle sizzle when a tiny bit of flour is dropped in, carefully place 2-3 chicken cutlets into the hot pan, ensuring you don't overcrowd it. Cook for 3-4 minutes per side until the chicken is beautifully golden brown and has a satisfyingly crisp crust. You'll notice a lovely aroma filling your kitchen. Remove the cooked chicken to a plate and cover loosely with foil to keep warm while you cook the remaining cutlets.

Sauté the Mushrooms: Add the remaining 1 tablespoon of olive oil to the same pan. Reduce the heat to medium. Add the sliced cremini mushrooms and sauté for 5-7 minutes, stirring occasionally. The mushrooms will release their moisture, then start to brown, becoming tender and deeply fragrant, taking on a rich, caramelised colour. You'll hear them sizzling gently and they'll smell wonderfully earthy.

Add Garlic and Deglaze: Push the mushrooms to one side of the pan and add the minced garlic to the cleared space. Cook for about 30 seconds until the garlic becomes aromatic and lightly golden, being careful not to burn it. Pour in the Halal chicken stock, unsweetened grape juice, and balsamic vinegar. Use a wooden spoon to scrape up any browned bits from the bottom of the pan – these are packed with flavour! The liquid will immediately start to bubble and release steam, and you'll smell the sharp, sweet notes of the vinegar mingling with the stock.

Simmer the Sauce: Bring the sauce to a gentle simmer and let it cook for 5-7 minutes, allowing the liquid to reduce slightly and the flavours to meld. The sauce will darken a little and thicken very slightly, coating the back of a spoon. It will smell deeply savoury and inviting.

Thicken and Finish the Sauce: Stir in the unsalted butter until it's fully melted and incorporated, adding a lovely richness and gloss to the sauce. Then, slowly whisk in the cornflour slurry. Continue to cook for another 1-2 minutes, stirring constantly, until the sauce thickens to your desired consistency – it should be velvety and able to cling to the chicken, but not overly gloopy. Once thickened, return the seared chicken cutlets to the pan, nestling them into the sauce. Allow them to warm through for 1-2 minutes, ensuring they are coated in the luscious sauce. Garnish generously with fresh chopped parsley before serving. The vibrant green of the parsley will pop against the rich brown sauce, and its fresh aroma will complete the dish.