Preheat the oven to 425°F.

Rub the chicken with salt and pepper.

Combine butter and chopped dill in a bowl.

Rub 2 tablespoons of dill butter on the chicken.

Loosen the skin of the chicken breasts and insert 1 tablespoon of dill butter under each breast.

Refrigerate the remaining butter.

Fill the chicken cavity with lemon quarters and a bunch of dill.

Place the chicken breast side up on a V-shaped rack in a roasting pan.

Roast the chicken for 25 minutes.

Remove the chicken from the oven and rub with 1 tablespoon of dill butter.

Place remaining butter lump on the chicken breast.

Add leeks, potatoes, and garlic to the roasting pan.

Pour chicken stock into the pan.

Turn the chicken breast side down.

Reduce the oven temperature to 350°F.

Roast for 50 to 60 more minutes, until the chicken is cooked through.

Check for doneness by piercing the thigh with a knife; juices should run clear.

Transfer the chicken to a carving board and let it rest for 15 minutes.

Check the potatoes for doneness; increase oven temperature to 400°F if needed.

Squeeze the garlic out of their skins.

Transfer potatoes, leeks, and garlic to a serving platter.

Carve the chicken and discard the lemon and dill from the cavity.

Garnish with dill and lemon wedges and sprinkle lemon zest on top.