Prepare the Chicken: Pat the chicken thighs completely dry with a paper towel. This is crucial for achieving crispy skin. Season both sides generously with salt and black pepper.

Sear the Chicken: Heat the olive oil in a large, heavy-bottomed skillet or cast-iron pan over a medium-high heat. Place the chicken thighs skin-side down in the hot pan. Don't overcrowd it; cook in two batches if necessary. Sear for 6-8 minutes without moving them, until the skin is deep golden brown and crisp. Flip and cook for another 5-6 minutes on the other side.

Set Chicken Aside: Once seared, remove the chicken from the pan and set it aside on a plate. Pour off all but 1 tablespoon of the rendered fat from the skillet.

Sauté the Aromatics: Reduce the heat to medium. Add the finely diced shallots to the pan and cook for 2-3 minutes until they have softened and become translucent. Add the minced garlic and fresh thyme, cooking for another minute until fragrant.

Build the Sauce Base: Pour in the chicken stock to deglaze the pan. Use a wooden spoon to scrape up any flavourful browned bits from the bottom. Let the stock simmer and reduce by about a third, for 2-3 minutes.

Combine Sauce Ingredients: Whisk in the Dijon mustard and dark brown sugar until the sugar has completely dissolved and the sauce is smooth.

Make it Creamy: Reduce the heat to low. Slowly pour in the double cream, whisking continuously until the sauce is well combined and velvety. Allow it to gently heat through, but do not let it come to a boil. What works best for me is to take the pan off the heat for a moment while I stir in the cream.

Finish Cooking the Chicken: Return the seared chicken thighs (and any accumulated juices from the plate) to the skillet, nestling them into the creamy sauce. Spoon some of the sauce over the top of the chicken.

Simmer to Perfection: Let everything simmer gently over a low heat for 5-7 minutes, or until the chicken is cooked through and the internal temperature reaches 74°C. You can find more safe cooking advice from the Food Standards Agency (FSA).

Rest and Garnish: Remove the pan from the heat. Let the chicken rest in the sauce for 5 minutes before serving. Garnish with freshly chopped parsley.