For the mango mousse, peel the mangos, cut them from the core and cut into pieces. Puree together with the powdered sugar and some lemon juice (about 1 tablespoon). Dissolve the gelatine in a small saucepan in some water under heat. Stir a few spoonfuls of mango puree into the gelatin and then stir all the gelatin into the remaining mango puree. Place the puree in the refrigerator for about 10 minutes. Whip the egg whites until stiff and also whip the whipped cream separately in a bowl until stiff. After the puree has chilled, fold in the whipped cream first and then the beaten egg whites.
Now refrigerate the mousse for about 2 hours.