Prepare the Chicken: Pat the chicken breasts dry with a paper towel. Season both sides generously with salt and pepper. If your chicken breasts are particularly thick, you can place them between two sheets of cling film and gently pound them to a more even thickness. This ensures they cook evenly.

Sear the Chicken: Heat the olive oil and 1 tablespoon of the butter in a large, heavy-bottomed frying pan or skillet over a medium-high heat. Once the butter is foaming, add the chicken breasts. Cook for 5-7 minutes on each side, until golden brown and cooked through. Don't overcrowd the pan; cook in two batches if necessary. Once cooked, transfer the chicken to a plate and set aside. Ensure the chicken is fully cooked by checking the internal temperature reaches 74°C, as recommended by the Food Standards Agency.

Sauté the Aromatics: Reduce the heat to medium. Add the remaining tablespoon of butter to the same pan. Add the finely chopped onion and cook for 3-4 minutes until softened and translucent. Add the minced garlic and cook for another minute until fragrant. I find that it's crucial not to let the garlic brown, as it can become bitter.

Deglaze the Pan: If using, pour in the white wine to deglaze the pan. Use a wooden spoon to scrape up any browned bits (the fond) from the bottom of the pan—this is where so much flavour is hiding! Let the wine bubble away and reduce by about half. This technique of deglazing is a game-changer for pan sauces.

Build the Sauce: Pour in the chicken stock and bring it to a simmer. Let it bubble gently for about 5 minutes to reduce slightly. This will concentrate the flavours.

Make it Creamy: Reduce the heat to low and stir in the double cream. Allow the sauce to warm through gently, but do not let it come to a rolling boil, as this can cause it to split.

Add Cheese and Herbs: Stir in the grated Parmesan cheese until it has completely melted into the sauce. Then, add the chopped fresh parsley and thyme leaves. Season the sauce with salt and pepper to your taste.

Finish the Dish: Return the seared chicken breasts (and any juices from the plate) to the pan. Spoon the creamy sauce over the chicken. Let everything simmer gently on low heat for 2-3 minutes, just to heat the chicken through and allow it to soak up some of the sauce. Serve immediately.