Heat the oil in a large deep frying pan or shallow casserole dish over a medium-high heat. Season the chicken thighs with salt and pepper then add to the pan skin-side down and cook for 12-15 minutes until the skin is golden and crisp. Flip and cook for 4 more minutes, then transfer to a plate.

Melt the butter in the same pan you cooked the chicken in - keeping the chicken fat in the pan - and and add the leeks. Cook, stirring occasionally, for 8-10 minutes until softened and starting to caramelise. Then add the garlic and thyme and cook for a minute more until fragrant.

Pour in the beans with their bean stock, fill the jar ⅓ the way with water and pour this in too, stir to combine. Stir in the truffle pesto, mustard and season generously with cracked black pepper. Nestle in the chicken thighs skin-side up to keep the skins crisp. Reduce the heat to low-medium and leave to simmer for 7-8 minutes. Serve with steamed greens or the suggestions given above.