Carefully crush half of the raspberries (do not crush the seeds) and pass through a sieve.
Beat the egg whites with the powdered sugar and salt until very stiff, then set aside to cool.
Place more than half of the biscuits close together on a fireproof plate and drizzle with half of the raspberry brandy.
Place the ice cream – perhaps cut to size – on top of the biscotti. Form half of the remaining raspberries with half of the puree on the ice cream, cover with the remaining biscotti. Drizzle with the remaining raspberry brandy. Spread thickly on all sides with the snow, draw patterns in the top of the egg whites with a fork.
Bake in the heated oven at 200 °C for about ten minutes on the second rack from the bottom.
Serve on the spot with the sauce and the remaining raspberries.