1. On a cutting board with a sharp knife, cut the leeks into thick slices; remove the peel from the limes and cut them into eighths; quarter the baby potatoes.
2. Set a non-stick frying pan over medium heat and add the 40 g butter.
3. When the butter melts, add the leeks and sauté until they begin to brown, seasoning with salt and freshly ground pepper.
4. When the leeks are ready, remove them from the pan and place them in a bowl together with the limes.
5. In a small bowl, put the 80 g butter together with the mustard, garlic powder, onion powder, lemon zest, salt and freshly ground pepper, and mix well.
6. Place the chicken on a cutting board; loosen the string tying the legs (without removing it completely), season the chicken inside and out with salt and freshly ground pepper, and fill it with the leeks and limes.
7. Tie the chicken legs again with the string and rub the butter mixture all over the chicken.
8. Put the chicken in a large ovenproof dish; arrange the baby potatoes and baby carrots around it, season with salt and freshly ground pepper, and pour in the chicken stock.
9. Bake in a preheated oven at 180°C for 55-60 minutes. Check from time to time, adding more liquid if needed.
10. In the last few minutes, you can raise the oven temperature to brown the chicken.
