Peel the mangoes and remove the pulp from the stone. Puree with powdered sugar and lemon juice. Soak the gelatin. Dissolve dripping wet in a pan over low heat. Add a few spoons of mango puree, then stir this mixture into the rest of the puree. Chill for 10 minutes.
Beat egg white and cream separately until stiff. First whipped cream, then whipped egg whites under the mango puree. Chill for at least 2 hours. Puree the raspberries with the sugar. Pass through a sieve as desired. Arrange the mousse on a plate and pour the raspberry puree over it.