Meringue-wiches

For the meringues: heat the oven to its lowest setting. Line 2 large baking trays with non-stick baking paper.

Whisk the egg whites and salt with an electric whisk until beginning to form peaks.

Gradually whisk in the caster sugar until thick and shiny.

Sift over a little of the icing sugar and gently fold in. Repeat until all the icing sugar is used and the mixture is thick and billowy.

Put the meringue into a piping bag with a shell nozzle and pipe about 30 rounds on the baking trays.

Put the meringues in the oven and bake for 1 hour 15 minutes-1 hour 45 minutes, until the meringues sound crisp when tapped underneath. Turn the oven off and leave to cool in the oven for a further 1 hour.

For the chocolate filling: put the chocolate and cream in a heatproof bowl over a pan of simmering (not boiling) water until the chocolate has melted.

Add the butter, stir until smooth, then remove from the heat and set aside to cool completely.