Preheat oven (electric cooker: 125 °C/circulating air: 100 °C/gas: level 1 or see manufacturer). Line a baking tray with baking paper. Sift icing sugar. Beat egg white and 1 pinch of salt until very stiff. Let the icing sugar trickle in.
Continue beating until a shiny mass is formed. Stir the raspberry jelly and 1 tsp. water until smooth, fold loosely into the beaten egg white.
Pour the beaten egg whites into a piping bag with a star-shaped spout and spray about 40 small tuffs onto the tray. Bake in a hot oven for about 1 hour. Then reduce the temperature to 100 °C and bake for about 1 more hour.
Switch off the oven and let the meringue cool down for about 1 1/2 hours.
Chop the couverture and melt in a hot water bath. Stir in butter. Spread one half of the meringue on the undersides with the chocolate cream. Add a second meringue to each half. Allow to set.