Prepare the Chicken: Pat the chicken breasts completely dry with a paper towel. This is crucial for getting a lovely golden-brown crust. In a shallow dish, mix together the plain flour, salt, and pepper. Dredge each chicken breast in the flour mixture, shaking off any excess.

Sear the Chicken: Heat the olive oil and 1 tablespoon of the butter in a large frying pan over a medium-high heat. Once the butter is melted and foaming, carefully place the floured chicken breasts in the pan. Don't overcrowd it; cook in two batches if necessary. Cook for 5-6 minutes per side, until golden brown and cooked through. I find that leaving them undisturbed for the first few minutes is key to a perfect crust. The internal temperature should reach 74°C (165°F) according to the Food Standards Agency. Remove the chicken from the pan and set aside on a plate.

Sauté the Aromatics: Reduce the heat to medium. Add the minced garlic and diced shallot (if using) to the pan. Sauté for about 1 minute until fragrant, being careful not to let the garlic burn.

Deglaze the Pan: Pour in the white wine (or extra chicken stock) to deglaze. Use a wooden spoon to scrape up all the delicious browned bits from the bottom of the pan. Let the wine simmer and reduce by about half, which should take 2-3 minutes.

Build the Sauce: Add the chicken stock, lemon juice, lemon zest, and fresh thyme sprigs to the pan. Bring to a simmer and let it cook for about 5 minutes, allowing the flavours to meld and the sauce to thicken slightly.

Finish the Dish: Reduce the heat to low. Return the chicken breasts (and any accumulated juices from the plate) to the pan. Add the remaining 2 tablespoons of butter and swirl the pan until it has melted and created a glossy, slightly thickened sauce. I used to struggle with this dish until I discovered this technique of adding the butter off the heat at the very end; it makes the sauce wonderfully rich and stable.

Serve: Spoon the sauce over the chicken. Garnish with fresh parsley and a few thin slices of lemon. Serve immediately.