Preheat the oven to 180°C, 350°F, Gas Mark 5.
Trim the ends off the lettuces and discard any brown outer leaves. Lay in a baking dish and pour over the stock. Tuck the herbs in and around the lettuces and season. Cover with foil and bake in the oven for 10 minutes.
Remove the foil and bake for a further 10-15 minutes or until the stock has reduced and the lettuces are very tender. Serve alongside roast chicken.
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