3 egg whites
1 cup icing sugar
3/4 cup whipping cream
1 1/2 cups fresh raspberries, divided
6 mint leaves, for garnish
In a standing mixer, whip egg whites to form medium peaks, then slowly add icing sugar until mixture becomes glossy with stiff peaks, about 8 minutes. With a rubber spatula, scrape into a large bowl and set aside.
In stand mixer, whip cream to form stiff peaks. Add to egg white mixture, folding gently so as not to incorporate too much air. Puree avocados with a hand blender or food processor and add to cream and egg white mixture. Fold all together and incorporate 250 ml (1 cup) of the raspberries.
Line a 23-by-12-cm (9-by-5-inch) baking dish with plastic wrap. Add semifreddo mixture, smoothing surface to flatten.
Freeze uncovered for at least 3 hours.
To serve, dip dish in about 5 cm (2 inches) of hot water to slightly melt edges. Dry baking dish and invert dessert onto serving plate. Remove plastic wrap and top with remaining raspberries and mint. Slice and serve.