Frozen chocolate mousse moulded in meringue

Bring the sugar and water to a boil, swirling by the handle until the liquid goes from cloudy to clear, and cook to the soft ball stage at 238F.

Whip the egg whites from slow to high, adding salt and cream of tartar once they foam, until stiff peaks.

Beat in the vanilla, then dribble in the hot sugar syrup at moderate speed for eight to ten minutes until the meringue holds erect walls.

Pipe three cups of the meringue into decorative strips no more than one and a half inches wide and one eighth inch thick on a lined sheet.

Bake on the lower and upper middle racks at 200F for about an hour to dry them out, then turn the oven off and leave the door ajar until cool.

Put both chocolates and the rum in a sauce pan set into a pan of simmering water taken off the heat and let it melt.

Fold an 18-inch piece of parchment lengthwise, cut along the fold into blunt-ended wedges five to six inches wide and two and a half inches at the blunt end, butter one side and line the mould; chill to set the butter.

Whip the melted chocolate into the remaining Italian meringue.

Over a bowl of ice, beat the heavy cream until the beaters leave light traces and it holds its shape.

Fold the cream into the chocolate meringue with a rubber spatula, cutting through the middle, flipping and rotating without deflating it.

Put a one inch layer of mousse in the mould, stand the meringues best side out around the edges a quarter inch apart, then alternate three quarter inch layers of mousse with pieces of meringue to the top and level it.

Cover with plastic wrap and freeze at least six hours.

Bend the paper back, fold the protruding meringue ends down, turn a chilled serving dish over the mould and unmould; peel away the paper and set the decorative centrepiece on top.