Mascarpone and Rum Trifle

350g / 12 oz mascarpone cheese
50g / 2 oz icing sugar
grated zest of 1 lemon
5 tbsp milk
5 tbsp rum
100g / 3 1/2 oz sponge fingers
150ml  / 1/4 pint double cream
icing sugar, to dust

For the meringues:
whites of 2 eggs
100g / 3 1/2 oz caster sugar

First make the meringues: preheat the oven to 140ºC / fan oven 120ºC / gas mark 1. Place the egg whites and sugar in a clean dry grease-free glass or ceramic bowl and sit this over a pan of gently simmering water. Whisk (preferably with an electric whisk) until very stiff and glossy.

Spoon the meringue mixture into a piping bag fitted with a large star nozzle and pipe 25 small swirls of meringue on a non-stick baking sheet. Place in the oven for 50 minutes, until firm but not coloured. Increase the oven setting to 200ºC / fan oven 180ºC / gas mark 6, and bake for a further 5 minutes until golden.

Meanwhile, make the filling. Beat together the mascarpone cheese, icing sugar, lemon zest and 2 tablespoons each of the milk and the rum. Cover the mixture and chill until needed.

Make the sponge base: mix together the remaining milk and rum. Dip the sponge fingers into the liquid and use to line the base of a glass serving dish.

Remove the meringues from the oven. Reserving 15 for decoration, roughly crumble the remaining meringues, fold these into the mascarpone mixture and spoon over the sponge base.

Whip the double cream until it forms soft peaks. Spread this on top of the mascarpone layer. Decorate the trifle with the reserved meringues and dust the top liberally with icing sugar before serving.