Does the White Chocolate Mint Mousse set enough to turn out of a mould? I want to serve it alongside a jelly on a plate. Many thanks.
Nigella's White Chcocolate Mint Mousse, along with any mousse that is not set with gelatine, is very unlikely to hold its shape if turned out of a mould. Mousses are usually made with whisked egg whites and/or cream and this gives them the light texture, but this can collapse quickly if not set with gelatine (or agar-agar). Gelatine can help to hold the mousse together, but if you use too much then the mousse can take on a slightly "chewy" texture.
If you are serving a plated dessert then you could serve a spoonful of mousse on the side of the jelly. A pair of dessert spoons (soup spoons for the US) can give a slightly rounded shape known as a "quenelle". Alternatively you could serve a panna cotta instead. This is a cream mixture set with gelatine and can often be turned out. Nigella has a trio of panna cottas (coffee, vanilla and Nutella) in her book Nigellissima.