Mascarpone cheese is a silky smooth Italian cream cheese and can be found quite easily in supermarkets. However, you could substitute regular cream cheese (ideally a smooth variety or slightly reduce the quantity so that the cream mixture is not too thick). Alternatively, crème fraîche or whipped ricotta cheese could also work as a substitute. Please remember that the end result will be very different to using mascarpone cheese, but I’m sure it would still taste wonderful.