Line a 22x10x6cm loaf tin with baking paper, or lightly grease a similar-sized mould with nonstick cooking spray.
Whisk the cream, icing sugar, lemon zest, lemon juice, brandy and liqueur in a mixing bowl until smooth and slightly thickened. Take care not to overbeat or the mixture will curdle.
Pour the cream into the prepared loaf tin, then cover with baking paper or cling film and freeze for eight hours or overnight.
Just before serving, remove the loaf tin from the freezer. Dip it in warm water for 1 second and turn the brandy cream out onto a ﬂat serving dish. Cut into slices and serve with the hot Christmas pudding.