Preheat the oven to 180°C.
Remove the strings from the chicken legs to release the thighs. Put it in a large roasting tray.
Rub the chicken with half the butter/margarine and drizzle with oil. Season with salt and pepper.
Peel the shallots and scatter them around the chicken together with the (unpeeled) garlic cloves.
Rub the bay leaves slightly with your fingers, then put one into the cavity of the chicken and scatter the rest into the tray.
Roast for 1 hour.
Spread the remaining butter over the chicken and drizzle with balsamic vinegar.
Turn the shallots around and baste them with the cooking jus.
Roast for about 15 minutes.
Test the chicken with a skewer at the thighs - if clear juice is coming out, when pricked, it’s cooked through. If it’s pink, you’ll need to roast it for another 5-10 minutes and test again.
When the chicken is done, remove it from the tray and rest for 15 minutes, under cover, before carving.
Serve the chicken pieces with the onion and balsamic sauce and your chosen side dishes.