Heat the oil in a large, shallow cast-iron pan and add the chicken legs, skin-side down. Cook on medium heat until the skin turns golden brown and crispy. When the skin is crispy, turn the legs over and cook on the flesh side until it has browned.

When the chicken legs are browned all over, remove them from the pan and set aside. Turn the heat down, add the garlic cloves and cook until soft and caramelised. Remove from the pan and set aside with the chicken.

Add the butter to the pan and melt gently. When the butter is foaming, add the flour and mix it in quickly with a wooden spoon. Cook the flour for a couple of minutes until it is golden and smelling biscuity. Then add the stock, a ladleful at a time, whisking in each addition to make sure there are no lumps. Allow the sauce to thicken each time before adding the next ladleful.

Once all the stock has been added allow the sauce to bubble and thicken. Then add the mustard, lemon juice, lemon zest and double cream. Stir and add the Maldon Garlic Sea Salt and some cracked black pepper. 

Place the chicken legs back into the sauce along with the garlic cloves, place the lid on the pan and gently simmer this at a very low temperature for approximately 10 minutes, or until the chicken legs are cooked through. The sauce should be glossy and creamy, but if it needs loosening add a splash of water or stock. 

Finally sprinkle over the tarragon and then serve with creamy mashed potato and greens.