Am I able to make the Chocolate Raspberry Pavlova base in advance and freeze it ?
Whilst it is possible to freeze pavlova meringues, such as Nigella's Chocolate Raspberry Pavlova (from Nigella Summer and on the Nigella website) it can be a little tricky to keep the meringue base in perfect condition and so it is not something we usually recommend. The meringue base is quite fragile and so can be damaged quite easily in the freezer if there are other items being put in and take nout of the freezer. Also sugar tends to attract moisture so the meringue can sometimes become a little sticky when thawed, though for a pavlova this is less of an issue as the centre is already quite soft and squidgy. Tha base can be made a day ahead and stored in an airtight ciontainer in a cool, dry place.
If you do want to try freezing the meringue base then make sure it is fully cold and then put it, still on its baking sheet, into the freezer. Once the base is frozen solid you can carefully remove it from the parchment and baking sheet and wrap it tightly in a double layer of clingfilm (plastic wrap) and a layer of foil before returning to the freezer and freezing for up to a month. To help protect the meringue it is a good idea to put the frozen meringue on a firm base before wrapping it - for example a freezer-proof plate or a round cake board. To thaw the meringue, unwrap it and put it on a serving plate and let it thaw for about 3 hours at room temperature.