As there is no gelatine or other setting agent in this Raffaello cheesecake, it is essential to keep beating the filling until it is quite stiff. If it falls off of a spoon easily then it needs to be beaten for longer. Keep on going until a metal spoon can stand up well in it. Make sure you use the correct ingredients too -that's full-fat cream cheese and double cream (48% fat). Lighter versions will affect the set of the cheesecake significantly.